Add Fl_Grid widget and test and demo programs

- FL/Fl_Grid.H: header file
- src/Fl_Grid.cxx: implementation

- examples/grid-simple.cxx: simple example program
- test/cube.cxx:            use Fl_Grid for layout
- test/grid_alignment.cxx:  test cell alignment and other functions
- test/grid_buttons.cxx:    demo program as discussed in fltk.general
- test/grid_login.cxx:      like test/flex_login.cxx but with Fl_Grid
- test/flex_login.cxx:      modified to match test/grid_login.cxx

9 files changed, 504 insertions, 105 deletions

diff --git a/test/.gitignore b/test/.gitignore
index 493ff3a75..cd29e2fca 100644
--- a/test/.gitignore
+++ b/test/.gitignore
@@ -52,6 +52,9 @@ fullscreen
 gl_overlay
 glpuzzle
 glut_test
+grid_alignment
+grid_buttons
+grid_login
 handle_events
 hello
 help_dialog
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index a44498c4d..e693399a4 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -92,6 +92,10 @@ if (OPENGL_FOUND)
   CREATE_EXAMPLE (glut_test glut_test.cxx "fltk_gl;fltk")
 endif()
 
+CREATE_EXAMPLE (grid_alignment grid_alignment.cxx fltk)
+CREATE_EXAMPLE (grid_buttons grid_buttons.cxx fltk)
+CREATE_EXAMPLE (grid_login grid_login.cxx fltk)
+
 if (OPENGL_FOUND)
   CREATE_EXAMPLE (handle_events handle_events.cxx "fltk_gl;fltk") # opt. Fl_Gl_Window
 else()
diff --git a/test/Makefile b/test/Makefile
index e73431b03..e69b8a9fd 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -76,6 +76,9 @@ CPPFILES =\
 	gl_overlay.cxx \
 	glpuzzle.cxx \
 	glut_test.cxx \
+	grid_alignment \
+	grid_buttons \
+	grid_login \
 	hello.cxx \
 	help_dialog.cxx \
 	icon.cxx \
@@ -161,6 +164,9 @@ ALL =	\
 	fltk-versions$(EXEEXT) \
 	fonts$(EXEEXT) \
 	forms$(EXEEXT) \
+	grid_alignment$(EXEEXT) \
+	grid_buttons$(EXEEXT) \
+	grid_login$(EXEEXT) \
 	hello$(EXEEXT) \
 	help_dialog$(EXEEXT) \
 	icon$(EXEEXT) \
@@ -437,6 +443,12 @@ forms$(EXEEXT): forms.o
 	$(CXX) $(ARCHFLAGS) $(CXXFLAGS) $(LDFLAGS) -o $@ forms.o $(LINKFLTKFORMS) $(LDLIBS)
 	$(OSX_ONLY) ../fltk-config --post $@
 
+grid_alignment$(EXEEXT): grid_alignment.o
+
+grid_buttons$(EXEEXT): grid_buttons.o
+
+grid_login$(EXEEXT): grid_login.o
+
 hello$(EXEEXT): hello.o
 
 help_dialog$(EXEEXT): help_dialog.o $(IMGLIBNAME)
diff --git a/test/cube.cxx b/test/cube.cxx
index 2dacb5976..bd69bc42c 100644
--- a/test/cube.cxx
+++ b/test/cube.cxx
@@ -3,7 +3,7 @@
 //
 // Modified to have 2 cubes to test multiple OpenGL contexts
 //
-// Copyright 1998-2021 by Bill Spitzak and others.
+// Copyright 1998-2023 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -26,7 +26,7 @@
 #include <FL/Fl_Slider.H>
 #include <FL/Fl_Sys_Menu_Bar.H>
 #include <FL/Fl_Printer.H>      // demo printing
-
+#include <FL/Fl_Grid.H>         // grid layout
 #include <stdlib.h>
 
 #if !HAVE_GL
@@ -39,8 +39,6 @@ public:
   cube_box(int x,int y,int w,int h,const char *l=0) :Fl_Box(FL_DOWN_BOX,x,y,w,h,l) {
     label("This demo does\nnot work without GL");
   }
-  void begin() {}
-  void end() {}
 };
 #else
 #include <FL/Fl_Gl_Window.H>
@@ -120,11 +118,8 @@ void cube_box::draw() {
   gl_draw(wire ? "Cube: wire" : "Cube: flat", -4.5f, -4.5f );
   glEnable(GL_DEPTH_TEST);
 
-  // if an OpenGL graphics driver is installed, give it a chance
-  // to draw additional graphics
-#if HAVE_GL
+  // draw additional FLTK widgets and graphics
   Fl_Gl_Window::draw();
-#endif
 }
 
 int cube_box::handle(int e) {
@@ -135,121 +130,128 @@ int cube_box::handle(int e) {
   return Fl_Gl_Window::handle(e);
 }
 
-#endif
+// callback for overlay button (Fl_Button on OpenGL scene)
+void show_info_cb(Fl_Widget*, void*) {
+  fl_message("This is an example of using FLTK widgets inside OpenGL windows.\n"
+             "Multiple widgets can be added to Fl_Gl_Windows. They will be\n"
+             "rendered as overlays over the scene.");
+}
+
+// overlay a button onto an OpenGL window (cube_box)
+void overlay_button(cube_box *cube) {
+  cube->begin();
+  Fl_Widget *w = new Fl_Button(10, 10, 120, 30, "FLTK over GL");
+  w->color(FL_FREE_COLOR);
+  w->box(FL_BORDER_BOX);
+  w->callback(show_info_cb);
+  cube->end();
+}
+
+#endif // HAVE_GL
 
 Fl_Window *form;
 Fl_Slider *speed, *size;
 Fl_Button *exit_button, *wire, *flat;
 cube_box  *lt_cube, *rt_cube;
-
 int done = 0; // set to 1 in exit button callback
 
 // exit button callback
-void exit_cb(Fl_Widget *, void *) {
+void exit_cb(Fl_Widget *w, void *) {
   done = 1;
+  w->window()->hide(); // necessary if built w/o GL
 }
 
 // print screen demo
-void print_cb(Fl_Widget *w, void *data)
-{
+void print_cb(Fl_Widget *w, void *data) {
   Fl_Printer printer;
   Fl_Window *win = Fl::first_window();
-  if(!win) return;
-  if( printer.start_job(1) ) return;
-  if( printer.start_page() ) return;
-  printer.scale(0.5,0.5);
-  printer.print_widget( win );
+  if (!win) return;
+  if (printer.start_job(1)) return;
+  if (printer.start_page()) return;
+  printer.scale(0.5, 0.5);
+  printer.print_widget(win);
   printer.end_page();
   printer.end_job();
 }
 
 // Create a form that allows resizing for A and C (GL windows) with B fixed size/centered:
 //
-//                  lt_grp                                rt_grp
 //      |<--------------------------------------->|<---------------------->|
-//      .          lt_cube            ct_grp      :       rt_cube          .
+//      .          lt_cube            center      :       rt_cube          .
 //      .            350                100       :         350            .
 //      .  |<------------------->|  |<-------->|  |<------------------->|  .
 //      ....................................................................
-//      :  .......................  ............  .......................  :
+//      :  .......................  ............  .......................  :  __
 //      :  :                     :  :          :  :                     :  :
-//      :  :          A          :  :    B     :  :          C          :  :
+//      :  :          A          :  :    B     :  :          C          :  :     h = 350
 //      :  :                     :  :          :  :                     :  :
 //      :  :.....................:  :..........:  :.....................:  :  __
 //      :..................................................................:  __ MARGIN
 //
-//      |  |
-//     MARGIN
-//
+//      |  |                     |  |          |  |
+//     MARGIN                    GAP           GAP
 
-#define MENUBAR_H 25            // menubar height
-#define MARGIN    20            // fixed margin around widgets
-#define MARGIN2   (MARGIN*2)
-#define MARGIN3   (MARGIN*3)
-
-void show_info_cb(Fl_Widget*, void*) {
-  fl_message("This is an example of using FLTK widgets inside OpenGL windows.\n"
-             "Multiple widgets can be added to Fl_Gl_Windows. They will be\n"
-             "rendered as overlays over the scene.");
-}
+#define MENUBAR_H 25    // menubar height
+#define MARGIN    20    // fixed margin around widgets
+#define GAP       20    // fixed gap between widgets
 
 void makeform(const char *name) {
   // Widget's XYWH's
-  int form_w = 800 + 4 * MARGIN;             // main window width
+  int form_w = 800 + 2 * MARGIN + 2 * GAP;   // main window width
   int form_h = 350 + MENUBAR_H + 2 * MARGIN; // main window height
-  int me_bar_x=0,                    me_bar_y=0,                me_bar_w=form_w,          me_bar_h=MENUBAR_H;                // menubar
-  int lt_grp_x=0,                    lt_grp_y=MENUBAR_H+MARGIN, lt_grp_w=350+100+MARGIN3, lt_grp_h=form_h-MENUBAR_H-MARGIN2; // left group
-  int lt_cub_x=lt_grp_x+MARGIN,      lt_cub_y=lt_grp_y,         lt_cub_w=350,             lt_cub_h=lt_grp_h;                 // left cube box (GL)
-  int ct_grp_x=lt_grp_x+350+MARGIN2, ct_grp_y=lt_grp_y,         ct_grp_w=100,             ct_grp_h=lt_grp_h;                 // center group
-  int rt_grp_x=lt_grp_x+lt_grp_w,    rt_grp_y=lt_grp_y,         rt_grp_w=350+MARGIN,      rt_grp_h=lt_grp_h;                 // right group
-  int rt_cub_x=rt_grp_x,             rt_cub_y=lt_grp_y,         rt_cub_w=350,             rt_cub_h=lt_grp_h;                 // right cube box (GL)
 
   // main window
   form = new Fl_Window(form_w, form_h, name);
-  form->begin();
-    // menu bar
-    Fl_Sys_Menu_Bar *menubar = new Fl_Sys_Menu_Bar(me_bar_x, me_bar_y, me_bar_w, me_bar_h);
-    menubar->add("File/Print window", FL_COMMAND+'p', print_cb);
-    menubar->add("File/Quit",         FL_COMMAND+'q', exit_cb);
-    // left group
-    Fl_Group *lt_grp = new Fl_Group(lt_grp_x, lt_grp_y, lt_grp_w, lt_grp_h);
-    lt_grp->begin();
-      // left GL window
-      lt_cube = new cube_box(lt_cub_x, lt_cub_y, lt_cub_w, lt_cub_h, 0);
+  // menu bar
+  Fl_Sys_Menu_Bar *menubar = new Fl_Sys_Menu_Bar(0, 0, form_w, MENUBAR_H);
+  menubar->add("File/Print window", FL_COMMAND+'p', print_cb);
+  menubar->add("File/Quit",         FL_COMMAND+'q', exit_cb);
+
+  // Fl_Grid (layout)
+  Fl_Grid *grid = new Fl_Grid(0, MENUBAR_H, form_w, 350 + 2 * MARGIN);
+  grid->layout(4, 4, MARGIN, GAP);
+  grid->box(FL_FLAT_BOX);
+
+  // set column and row weights to control resizing behavior
+  int cwe[] = {50,  0,  0, 50}; // column weights
+  int rwe[] = { 0,  0, 50,  0}; // row weights
+  grid->col_weight(cwe, 4);     // set weights for resizing
+  grid->row_weight(rwe, 4);     // set weights for resizing
+
+  // set non-default gaps for special layout purposes and labels
+  grid->row_gap(0,  0);         // no gap below wire button
+  grid->row_gap(2, 50);         // gap below sliders for labels
 
-      lt_cube->begin();
-      Fl_Widget *w = new Fl_Button(10, 10, 120, 30, "FLTK over GL");
-      w->color(FL_FREE_COLOR);
-      w->box(FL_BORDER_BOX );
-      w->callback(show_info_cb);
-      lt_cube->end();
+  // left GL window
+  lt_cube = new cube_box(0, 0, 350, 350);
 
-      // center group
-      Fl_Group *ct_grp = new Fl_Group(ct_grp_x, ct_grp_y, ct_grp_w, ct_grp_h);
-      ct_grp->begin();
-        wire  = new Fl_Radio_Light_Button(ct_grp_x, ct_grp_y,            100, 25, "Wire");
-        flat  = new Fl_Radio_Light_Button(ct_grp_x, wire->y()+wire->h(), 100, 25, "Flat");
-        speed = new Fl_Slider(FL_VERT_SLIDER, ct_grp_x,           flat->y()+flat->h()+MARGIN, 40, 200, "Speed");
-        size  = new Fl_Slider(FL_VERT_SLIDER, ct_grp_x+40+MARGIN, flat->y()+flat->h()+MARGIN, 40, 200, "Size");
-        exit_button = new Fl_Button(ct_grp_x, form_h-MARGIN-25, 100, 25, "Exit");
-        exit_button->callback(exit_cb);
-      ct_grp->end();
-      ct_grp->resizable(speed);      // only sliders resize vertically, not buttons
-    lt_grp->end();
-    lt_grp->resizable(lt_cube);
-    // right group
-    Fl_Group *rt_grp = new Fl_Group(rt_grp_x, rt_grp_y, rt_grp_w, rt_grp_h);
-    rt_grp->begin();
-      // right GL window
-      rt_cube = new cube_box(rt_cub_x, rt_cub_y, rt_cub_w, rt_cub_h, 0);
-    rt_grp->end();
-    rt_grp->resizable(rt_cube);
-    // right resizer
-    Fl_Box *rt_resizer = new Fl_Box(rt_grp_x-5, rt_grp_y, 10, rt_grp_h);
-    rt_resizer->box(FL_NO_BOX);
+  // center group
+  wire  = new Fl_Radio_Light_Button(    0, 0, 100, 25, "Wire");
+  flat  = new Fl_Radio_Light_Button(    0, 0, 100, 25, "Flat");
+  speed = new Fl_Slider(FL_VERT_SLIDER, 0, 0,  40, 90, "Speed");
+  size  = new Fl_Slider(FL_VERT_SLIDER, 0, 0,  40, 90, "Size");
+  exit_button = new Fl_Button(          0, 0, 100, 25, "Exit");
+  exit_button->callback(exit_cb);
+
+  // right GL window
+  rt_cube = new cube_box(0, 0, 350, 350);
+
+  // assign widgets to grid positions (R=row, C=col) and sizes
+  // RS=rowspan, CS=colspan: R, C, RS, CS, optional alignment
+  grid->widget(lt_cube,      0, 0,  4,  1);
+  grid->widget(wire,         0, 1,  1,  2);
+  grid->widget(flat,         1, 1,  1,  2);
+  grid->widget(speed,        2, 1,  1,  1, FL_GRID_VERTICAL);
+  grid->widget(size,         2, 2,  1,  1, FL_GRID_VERTICAL);
+  grid->widget(exit_button,  3, 1,  1,  2);
+  grid->widget(rt_cube,      0, 3,  4,  1);
+
+#if HAVE_GL
+  overlay_button(lt_cube);  // overlay a button onto the OpenGL window
+#endif // HAVE_GL
 
   form->end();
-  form->resizable(rt_resizer);
+  form->resizable(grid);
   form->size_range(form->w(), form->h()); // minimum window size
 }
 
@@ -257,29 +259,27 @@ int main(int argc, char **argv) {
   Fl::use_high_res_GL(1);
   Fl::set_color(FL_FREE_COLOR, 255, 255, 0, 75);
   makeform(argv[0]);
-  speed->bounds(4,0);
-#if HAVE_GL
+  speed->bounds(4, 0);
   speed->value(lt_cube->speed = rt_cube->speed = 1.0);
-#else
-  speed->value(lt_cube->speed = rt_cube->speed = 0.0);
-#endif
-  size->bounds(4,0.01);
-  size->value(lt_cube->size = rt_cube->size = 3.0);
+  size->bounds(4, 0.2);
+  size->value(lt_cube->size = rt_cube->size = 2.0);
   flat->value(1); lt_cube->wire = 0; rt_cube->wire = 1;
-  form->label("cube");
+  form->label("Cube Demo");
   form->show(argc,argv);
   lt_cube->show();
   rt_cube->show();
+
 #if 0
   // This demonstrates how to manipulate OpenGL contexts.
   // In this case the same context is used by multiple windows (I'm not
   // sure if this is allowed on Win32, can somebody check?).
-  // This fixes a bug on the XFree86 3.0 OpenGL where only one context
-  // per program seems to work, but there are probably better uses for
-  // this!
+  // This fixes a bug on the XFree86 3.0 OpenGL where only one context per
+  // program seems to work, but there are probably better uses for this!
   lt_cube->make_current(); // causes context to be created
   rt_cube->context(lt_cube->context()); // share the contexts
 #endif
+
+#if HAVE_GL
   for (;;) {
     if (form->visible() && speed->value()) {
       if (!Fl::check()) break;   // returns immediately
@@ -295,4 +295,7 @@ int main(int argc, char **argv) {
     if (done) break; // exit button was clicked
   }
   return 0;
+#else
+  return Fl::run();
+#endif
 }
diff --git a/test/flex_login.cxx b/test/flex_login.cxx
index be72e6c8b..3f6dc77d8 100644
--- a/test/flex_login.cxx
+++ b/test/flex_login.cxx
@@ -2,7 +2,7 @@
 // Fl_Flex demo program for the Fast Light Tool Kit (FLTK).
 //
 // Copyright 2020 by Karsten Pedersen
-// Copyright 2022 by Bill Spitzak and others.
+// Copyright 2022-2023 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -32,7 +32,10 @@ Fl_Button *create_button(const char *caption) {
 
 void buttons_panel(Fl_Flex *parent) {
   new Fl_Box(0, 0, 0, 0, "");
-  Fl_Box *w = new Fl_Box(0, 0, 0, 0, "Welcome to Flex Login");
+  Fl_Box *title = new Fl_Box(0, 0, 0, 0, "Welcome to Fl_Flex");
+  title->align(FL_ALIGN_CENTER);
+  title->labelfont(FL_BOLD + FL_ITALIC);
+  title->labelsize(16);
 
   Fl_Flex *urow = new Fl_Flex(Fl_Flex::ROW);
   {
@@ -71,7 +74,7 @@ void buttons_panel(Fl_Flex *parent) {
 
   Fl_Box *b = new Fl_Box(0, 0, 0, 0, "");
 
-  parent->fixed(w, 60);
+  parent->fixed(title, 60);
   parent->fixed(urow, 30);
   parent->fixed(prow, 30);
   parent->fixed(pad, 1);
@@ -95,7 +98,7 @@ void middle_panel(Fl_Flex *parent) {
 
   new Fl_Box(0, 0, 0, 0, "");
 
-  parent->fixed(box, 200);
+  parent->fixed(box, 150);
   parent->fixed(spacer, 10);
   parent->fixed(bp, 300);
 }
@@ -119,21 +122,21 @@ void mainPanel(Fl_Flex *parent) {
 
 int main(int argc, char **argv) {
 
-  Fl_Window *window = new Fl_Double_Window(100, 100, "Simple GUI Example");
+  Fl_Window *win = new Fl_Double_Window(100, 100, "Fl_Flex \"Login\" Layout");
 
   Fl_Flex *col = new Fl_Flex(5, 5, 90, 90, Fl_Flex::COLUMN);
   mainPanel(col);
   col->end();
 
-  window->resizable(col);
-  window->color(fl_rgb_color(250, 250, 250));
-  window->end();
+  win->resizable(col);
+  win->color(fl_rgb_color(250, 250, 250));
+  win->end();
 
-  window->resize(0, 0, 640, 480);
-  window->size_range(550, 250);
-  window->show(argc, argv);
+  win->resize(0, 0, 600, 300);   // same size as grid_login
+  win->size_range(550, 250);
+  win->show(argc, argv);
 
   int ret = Fl::run();
-  delete window; // not necessary but useful to test for memory leaks
+  delete win; // not necessary but useful to test for memory leaks
   return ret;
 }
diff --git a/test/grid_alignment.cxx b/test/grid_alignment.cxx
new file mode 100644
index 000000000..59a5368c3
--- /dev/null
+++ b/test/grid_alignment.cxx
@@ -0,0 +1,203 @@
+//
+// Fl_Grid demo program for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 2021 by Albrecht Schlosser
+// Copyright 2022-2023 by Bill Spitzak and others.
+//
+// This library is free software. Distribution and use rights are outlined in
+// the file "COPYING" which should have been included with this file.  If this
+// file is missing or damaged, see the license at:
+//
+//     https://www.fltk.org/COPYING.php
+//
+// Please see the following page on how to report bugs and issues:
+//
+//     https://www.fltk.org/bugs.php
+//
+
+//
+// This program tests several different alignment features of Fl_Grid.
+//
+
+#include <FL/Fl.H>
+#include <FL/Fl_Double_Window.H>
+#include <FL/Fl_Grid.H>
+#include <FL/Fl_Button.H>
+#include <FL/Fl_Input.H>
+#include <FL/Fl_Box.H>
+
+// Test function to change the layout (executed by timer callback)
+
+#define TEST_RELAYOUT (0)
+#define TEST_REMOVE_NOTIFY (0)
+
+#if (TEST_RELAYOUT)
+void relayout_cb(void *v) {
+  Fl_Grid *grid = (Fl_Grid *)v;
+  grid->layout(5, 5, 8, 4);
+  grid->margin(10, 20, 30, 40);
+  grid->layout();
+  grid->redraw();
+}
+#endif
+
+#if TEST_REMOVE_NOTIFY
+
+void remove_cb(void *v) {
+  static int n = 10;
+  n--;
+  Fl_Grid *grid = (Fl_Grid *)v;
+#if (0)             // test 1: remove() the widget -- leaks memory (!)
+  grid->remove(n);
+#else               // test 2: delete the widget -- no leak
+  delete grid->child(0);
+#endif
+  if (n > 0)
+    Fl::repeat_timeout(0.3, remove_cb, v);
+}
+
+#endif
+
+int main(int argc, char **argv) {
+  Fl_Grid::Cell *c;
+  Fl_Box *b;
+  Fl_Double_Window *win = new Fl_Double_Window(440, 350, "FLTK 1.4.0 - Fl_Grid Alignment Test");
+  Fl_Grid *grid = new Fl_Grid(10, 10, 420, 330);
+  grid->layout(7, 7, 8, 4);       // cols, rows, margin, gap
+  grid->box(FL_FLAT_BOX);
+  grid->color(FL_WHITE);
+
+  // add boxes (top and bottom rows)
+
+  for (int col = 0; col < 7; col++) {
+    grid->col_width(col, 50);
+    b = new Fl_Box(0, 0, 20, 20);   // variable size
+    if (col == 5) {
+      b->size(4, 20);               // reduce width
+      grid->col_width(col, 4);      // new min. width
+      grid->col_weight(col, 0);     // no hor. resizing
+    }
+    b->box(FL_FLAT_BOX);
+    b->color(FL_BLUE);
+    grid->widget(b, 0, col);
+
+    if (col == 5)
+      b = new Fl_Box(0, 0, 4, 20);   // variable size
+    else
+      b = new Fl_Box(0, 0, 20, 20);   // variable size
+    b->box(FL_FLAT_BOX);
+    b->color(FL_RED);
+    grid->widget(b, 6, col);
+  }
+
+  // add boxes (left and right columns)
+
+  grid->row_height(0, 40);
+  grid->row_height(6, 40);
+
+  for (int row = 1; row < 6; row++) {
+    grid->row_height(row, 40);
+    b = new Fl_Box(0, 0, 20, 20);           // fixed size, see alignment below
+    b->box(FL_FLAT_BOX);
+    b->color(FL_RED);
+    switch(row) {
+      case 1: grid->widget(b, row, 0, FL_GRID_FILL); break;
+      case 2: grid->widget(b, row, 0, FL_ALIGN_CENTER); break;
+      case 3: grid->widget(b, row, 0, FL_ALIGN_BOTTOM_RIGHT); break;
+      case 4: grid->widget(b, row, 0, FL_ALIGN_BOTTOM_RIGHT); break;
+      case 5: grid->widget(b, row, 0, FL_ALIGN_TOP_RIGHT); break;
+      default: break;
+    }
+
+    b = new Fl_Box(0, 0, 20, 20);
+    b->box(FL_FLAT_BOX);
+    b->color(FL_GREEN);
+    c = grid->widget(b, row, 6, FL_ALIGN_CENTER);
+  }
+
+  // two more boxes to demonstrate widget alignment inside the cell
+
+  for (int row = 4; row < 6; row++) {
+    b = new Fl_Box(0, 0, 20, 20);           // fixed size, see alignment below
+    b->box(FL_FLAT_BOX);
+    b->color(FL_MAGENTA);
+    c = grid->widget(b, row, 1);            // default alignment: FL_GRID_FILL
+    if (row == 4)
+      c->align(FL_ALIGN_BOTTOM_LEFT);       // alignment uses widget size
+    if (row == 5)
+      c->align(FL_ALIGN_TOP_LEFT);          // alignment uses widget size
+  }
+
+  // one vertical box (line), spanning 5 rows
+
+  b = new Fl_Box(0, 0, 2, 2);               // extends vertically
+  b->box(FL_FLAT_BOX);
+  b->color(FL_BLACK);
+  grid->widget(b, 1, 5, 5, 1, FL_GRID_VERTICAL | FL_ALIGN_RIGHT);
+
+  // add a textbox with label or title, spanning 5 cells, centered
+
+  b = new Fl_Box(0, 0, 1, 1);               // variable size
+  b->label("Hello, Fl_Grid !");
+  b->labelfont(FL_BOLD + FL_ITALIC);
+  b->labelsize(30);
+  b->labeltype(FL_SHADOW_LABEL);
+  grid->widget(b, 1, 1, 1, 5);              // rowspan = 1, colspan = 5
+
+  // add a footer textbox, spanning 3 cells, right aligned
+
+  b = new Fl_Box(0, 0, 1, 10);               // variable size
+  b->label("FLTK/test/grid_alignment.cxx");
+  b->labelfont(FL_COURIER);
+  b->labelsize(11);
+  b->align(FL_ALIGN_INSIDE | FL_ALIGN_RIGHT);
+  grid->widget(b, 5, 2, 1, 3, FL_GRID_HORIZONTAL | FL_ALIGN_BOTTOM);
+
+  // input widgets with fixed size and alignment inside the cell
+
+  Fl_Input *i1 = new Fl_Input(0, 0, 100, 30, "Username:");
+  c = grid->widget(i1, 2, 3, 1, 2);         // widget, col, row, colspan, rowspan
+  c->align(FL_GRID_HORIZONTAL);             // widget alignment in cell
+
+  Fl_Input *i2 = new Fl_Input(0, 0, 100, 30, "Password:");
+  c = grid->widget(i2, 3, 3, 1, 2);         // widget, col, row, colspan, rowspan
+  c->align(FL_GRID_HORIZONTAL);             // widget alignment in cell
+
+  // the login button spans 2 columns
+
+  Fl_Button *bt = new Fl_Button(0, 0, 10, 30, "Login");
+  grid->widget(bt, 4, 3, 1, 2, FL_GRID_HORIZONTAL); // widget, col, row, colspan, rowspan, alignment
+
+  grid->row_weight(1, 90);
+  grid->row_weight(2,  0);
+  grid->row_weight(3,  0);
+  grid->row_weight(4,  0);
+
+  grid->col_weight(0, 30);
+  grid->col_weight(4, 90);
+
+  grid->row_gap(5, 12);
+
+  grid->end();
+  grid->layout();
+  grid->debug(0);
+  // grid->show_grid(1);     // enable to display grid helper lines
+  win->end();
+  win->resizable(grid);
+  win->size_range(440, 350);
+  win->show(argc, argv);
+
+#if (TEST_RELAYOUT)
+  Fl::add_timeout(5.0, relayout_cb, grid);
+#endif
+
+#if (TEST_REMOVE_NOTIFY)
+  Fl::add_timeout(3.0, remove_cb, grid);
+#endif
+
+  // return Fl::run();
+  int ret = Fl::run();
+  grid->clear_layout();
+  delete win;
+  return ret;
+}
diff --git a/test/grid_buttons.cxx b/test/grid_buttons.cxx
new file mode 100644
index 000000000..a00a69a64
--- /dev/null
+++ b/test/grid_buttons.cxx
@@ -0,0 +1,75 @@
+//
+// Fl_Grid demo program for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 2021 by Albrecht Schlosser
+// Copyright 2022-2023 by Bill Spitzak and others.
+//
+// This library is free software. Distribution and use rights are outlined in
+// the file "COPYING" which should have been included with this file.  If this
+// file is missing or damaged, see the license at:
+//
+//     https://www.fltk.org/COPYING.php
+//
+// Please see the following page on how to report bugs and issues:
+//
+//     https://www.fltk.org/bugs.php
+//
+
+// Q: How to achieve a spaced out layout?
+// https://groups.google.com/g/fltkgeneral/c/haet7hOQR0g
+
+// A: We use an Fl_Grid with 1 x 7 cells (5 buttons) as requested:
+// [New] [Options] <gap> [About] [Help] <gap> [Quit]
+
+#include <FL/Fl.H>
+#include <FL/Fl_Double_Window.H>
+#include <FL/Fl_Grid.H>
+#include <FL/Fl_Button.H>
+
+int main(int argc, char **argv) {
+
+  Fl_Double_Window *win = new Fl_Double_Window(460, 200, "Fl_Grid Row with 5 Buttons");
+
+  Fl_Grid *grid = new Fl_Grid(0, 0, win->w(), 50);
+  grid->layout(1, 7, 10, 10);
+
+  // create the buttons
+
+  Fl_Button *b0 = new Fl_Button(0, 0, 80, 30, "New");
+  Fl_Button *b1 = new Fl_Button(0, 0, 80, 30, "Options");
+  Fl_Button *b3 = new Fl_Button(0, 0, 80, 30, "About");
+  Fl_Button *b4 = new Fl_Button(0, 0, 80, 30, "Help");
+  Fl_Button *b6 = new Fl_Button(0, 0, 80, 30, "Quit");
+
+  grid->end();
+
+  // assign buttons to grid positions
+
+  grid->widget(b0, 0, 0);
+  grid->widget(b1, 0, 1); grid->col_gap(1, 0);
+  grid->widget(b3, 0, 3);
+  grid->widget(b4, 0, 4); grid->col_gap(4, 0);
+  grid->widget(b6, 0, 6);
+
+  // set column weights for resizing (only empty columns resize)
+
+  int weight[] = { 0, 0, 50, 0, 0, 50, 0 };
+  grid->col_weight(weight, 7);
+
+  grid->end();
+  // grid->show_grid(1);     // enable to display grid helper lines
+
+  // add content ...
+
+  Fl_Group *g1 = new Fl_Group(0, 50, win->w(), win->h() - 50);
+  // add more widgets ...
+
+  win->end();
+  win->resizable(g1);
+  win->size_range(win->w(), 100);
+  win->show(argc, argv);
+
+  int ret = Fl::run();
+  delete win; // not necessary but useful to test for memory leaks
+  return ret;
+}
diff --git a/test/grid_login.cxx b/test/grid_login.cxx
new file mode 100644
index 000000000..fb10bb649
--- /dev/null
+++ b/test/grid_login.cxx
@@ -0,0 +1,94 @@
+//
+// Fl_Grid demo program for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 2021 by Albrecht Schlosser
+// Copyright 2022-2023 by Bill Spitzak and others.
+//
+// This library is free software. Distribution and use rights are outlined in
+// the file "COPYING" which should have been included with this file.  If this
+// file is missing or damaged, see the license at:
+//
+//     https://www.fltk.org/COPYING.php
+//
+// Please see the following page on how to report bugs and issues:
+//
+//     https://www.fltk.org/bugs.php
+//
+
+#include <FL/Fl.H>
+#include <FL/Fl_Double_Window.H>
+#include <FL/Fl_Grid.H>
+#include <FL/Fl_Button.H>
+#include <FL/Fl_Input.H>
+#include <FL/Fl_Box.H>
+
+int main(int argc, char **argv) {
+
+  Fl_Double_Window *win = new Fl_Double_Window(480, 200, "Fl_Grid \"Login\" Layout");
+
+  // Fl_Grid of 6 x 6 cells, margin 2 and gap 2
+
+  Fl_Grid *grid = new Fl_Grid(5, 5, 470, 190);
+  grid->layout(6, 6, 2, 2);  // 6 rows, 6 columns, margin 2, gap 2
+
+  // image (150x200) in left column
+
+  Fl_Box *ibox = new Fl_Box(0, 0, 150, 200, "Image");
+  ibox->box(FL_BORDER_BOX);
+  ibox->color(fl_rgb_color(0, 200, 0));
+  grid->widget(ibox, 1, 1, 4, 1, FL_GRID_CENTER);
+
+  // the title spans 2 columns (3 - 4)
+
+  Fl_Box *title = new Fl_Box(0, 0, 200, 60);
+  title->label("Welcome to Fl_Grid");
+  title->align(FL_ALIGN_CENTER);
+  title->labelfont(FL_BOLD + FL_ITALIC);
+  title->labelsize(16);
+  grid->widget(title, 1, 3, 1, 2, FL_GRID_HORIZONTAL | FL_GRID_CENTER);
+
+  grid->col_width(2, 90);  // placeholder for labels
+
+  // input widgets with fixed height and horizontal stretching
+
+  Fl_Input *i1 = new Fl_Input(0, 0, 150, 30, "Username:");
+  grid->widget(i1, 2, 3, 1, 2, FL_GRID_HORIZONTAL);
+  grid->row_gap(2, 10); // gap below username
+
+  Fl_Input *i2 = new Fl_Input(0, 0, 150, 30, "Password:");
+  grid->widget(i2, 3, 3, 1, 2, FL_GRID_HORIZONTAL);
+  grid->row_gap(3, 10); // gap below password
+
+  // register and login buttons
+
+  Fl_Button *btr = new Fl_Button(0, 0, 80, 30, "Register");
+  grid->widget(btr, 4, 3, 1, 1, FL_GRID_HORIZONTAL);
+  grid->col_gap(3, 20); // gap right of the register button
+
+  Fl_Button *btl = new Fl_Button(0, 0, 80, 30, "Login");
+  grid->widget(btl, 4, 4, 1, 1, FL_GRID_HORIZONTAL);
+
+  // set column and row weights for resizing behavior (optional)
+
+  int cw[] = { 20,  0,  0, 10, 10, 20};  // column weights
+  int rw[] = { 10,  0,  0,  0,  0, 10};  // row weights
+  grid->col_weight(cw, 6);
+  grid->row_weight(rw, 6);
+
+  grid->end();
+  grid->layout();
+  // grid->debug(1);
+  // grid->show_grid(1);     // enable to display grid helper lines
+  win->end();
+  grid->color(fl_rgb_color(250, 250, 250));
+  win->color(fl_rgb_color(250, 250, 250));
+
+  win->resizable(grid);
+  win->resize(0, 0, 600, 300);   // same size as flex_login
+  win->size_range(550, 250);
+  win->show(argc, argv);
+
+  int ret = Fl::run();
+  delete win; // not necessary but useful to test for memory leaks
+  return ret;
+}
diff --git a/test/makedepend b/test/makedepend
index 6d57bc9a2..dfd430bf3 100644
--- a/test/makedepend
+++ b/test/makedepend
@@ -539,6 +539,7 @@ cube.o: ../FL/fl_config.h
 cube.o: ../FL/Fl_Device.H
 cube.o: ../FL/Fl_Export.H
 cube.o: ../FL/Fl_Gl_Window.H
+cube.o: ../FL/Fl_Grid.H
 cube.o: ../FL/Fl_Group.H
 cube.o: ../FL/Fl_Image.H
 cube.o: ../FL/Fl_Light_Button.H
@@ -550,6 +551,7 @@ cube.o: ../FL/Fl_Plugin.H
 cube.o: ../FL/Fl_Preferences.H
 cube.o: ../FL/Fl_Printer.H
 cube.o: ../FL/Fl_Radio_Light_Button.H
+cube.o: ../FL/Fl_Rect.H
 cube.o: ../FL/Fl_Slider.H
 cube.o: ../FL/Fl_String.H
 cube.o: ../FL/Fl_Sys_Menu_Bar.H