Fluid: restructuring and rejuvenation of the source code.

* Add classes for application and project
* Removed all globals from Fluid.h
* Extracting args and project history into their own classes
* Moving globals into Application class
* Initialize values inside headers for some classes.
* Undo functionality wrapped in a class inside Project.
* File reader and writer are now linked to a project.
* Avoid global project access
* Nodes (former Types) will be managed by a new Tree class.
* Removed static members (hidden globals) form Node/Fl_Type.
* Adding Tree iterator.
* Use nullptr instead of 0, NULL, or 0L
* Renamed Fl_..._Type to ..._Node, FL_OVERRIDE -> override
* Renaming ..._type to ...::prototype
* Splitting Widget Panel into multiple files.
* Moved callback code into widget panel file.
* Cleaning up Fluid_Image -> Image_asset
* Moving Fd_Snap_Action into new namespace fld::app::Snap_Action etc.
* Moved mergeback into proj folder.
* `enum ID` is now `enum class Type`.

1 files changed, 166 insertions, 0 deletions

diff --git a/fluid/nodes/Button_Node.cxx b/fluid/nodes/Button_Node.cxx
new file mode 100644
index 000000000..c1ac26e95
--- /dev/null
+++ b/fluid/nodes/Button_Node.cxx
@@ -0,0 +1,166 @@
+//
+// Button Node code for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 1998-2025 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
+//
+
+/**
+ \file Bottun_Node.cxx
+
+ Node prototypes for Fl_Button based classes. Those are used by the Node
+ Factory to generate the scene from project files or user input.
+ */
+
+#include "nodes/Button_Node.h"
+
+#include "Fluid.h"
+#include "app/Snap_Action.h"
+#include "io/Project_Reader.h"
+#include "io/Project_Writer.h"
+
+#include <FL/Fl.H>
+#include <FL/Fl_Button.H>
+#include <FL/Fl_Check_Button.H>
+#include <FL/Fl_Menu_Item.H>
+#include <FL/Fl_Return_Button.H>
+#include <FL/Fl_Repeat_Button.H>
+#include <FL/Fl_Round_Button.H>
+
+#include <stdlib.h>
+
+// ---- Button Nodes --------------------------------------------------- MARK: -
+
+
+// ---- Button ----
+
+Button_Node Button_Node::prototype;
+
+static Fl_Menu_Item buttontype_menu[] = {
+  {"Normal", 0, nullptr, (void*)nullptr},
+  {"Toggle", 0, nullptr, (void*)FL_TOGGLE_BUTTON},
+  {"Radio", 0, nullptr, (void*)FL_RADIO_BUTTON},
+  {nullptr}
+};
+
+Fl_Menu_Item *Button_Node::subtypes() {
+  return buttontype_menu;
+}
+
+void Button_Node::ideal_size(int &w, int &h) {
+  auto layout = Fluid.proj.layout;
+  h = layout->labelsize + 8;
+  w = layout->labelsize * 4 + 8;
+  fld::app::Snap_Action::better_size(w, h);
+}
+
+Fl_Widget *Button_Node::widget(int x, int y, int w, int h) {
+  return new Fl_Button(x, y, w, h, "Button");
+}
+
+void Button_Node::write_properties(fld::io::Project_Writer &f) {
+  Widget_Node::write_properties(f);
+  Fl_Button *btn = (Fl_Button*)o;
+  if (btn->compact()) {
+    f.write_string("compact");
+    f.write_string("%d", btn->compact());
+  }
+}
+
+void Button_Node::read_property(fld::io::Project_Reader &f, const char *c) {
+  Fl_Button *btn = (Fl_Button*)o;
+  if (!strcmp(c, "compact")) {
+    btn->compact((uchar)atol(f.read_word()));
+  } else {
+    Widget_Node::read_property(f, c);
+  }
+}
+
+void Button_Node::copy_properties() {
+  Widget_Node::copy_properties();
+  Fl_Button *s = (Fl_Button*)o, *d = (Fl_Button*)live_widget;
+  d->compact(s->compact());
+}
+
+
+// ---- Return Button ----
+
+void Return_Button_Node::ideal_size(int &w, int &h) {
+  auto layout = Fluid.proj.layout;
+  h = layout->labelsize + 8;
+  w = layout->labelsize * 4 + 8 + h; // make room for the symbol
+  fld::app::Snap_Action::better_size(w, h);
+}
+
+Fl_Widget *Return_Button_Node::widget(int x, int y, int w, int h) {
+  return new Fl_Return_Button(x, y, w, h, "Button");
+}
+
+Return_Button_Node Return_Button_Node::prototype;
+
+
+// ---- Repeat Button ----
+
+Fl_Widget *Repeat_Button_Node::widget(int x, int y, int w, int h) {
+  return new Fl_Repeat_Button(x, y, w, h, "Button");
+}
+
+Repeat_Button_Node Repeat_Button_Node::prototype;
+
+
+// ---- Light Button ----
+
+void Light_Button_Node::ideal_size(int &w, int &h) {
+  auto layout = Fluid.proj.layout;
+  h = layout->labelsize + 8;
+  w = layout->labelsize * 4 + 8 + layout->labelsize; // make room for the light
+  fld::app::Snap_Action::better_size(w, h);
+}
+
+Fl_Widget *Light_Button_Node::widget(int x, int y, int w, int h) {
+  return new Fl_Light_Button(x, y, w, h, "Button");
+}
+
+Light_Button_Node Light_Button_Node::prototype;
+
+
+// ---- Check Button ----
+
+void Check_Button_Node::ideal_size(int &w, int &h) {
+  auto layout = Fluid.proj.layout;
+  h = layout->labelsize + 8;
+  w = layout->labelsize * 4 + 8 + layout->labelsize; // make room for the symbol
+  fld::app::Snap_Action::better_size(w, h);
+}
+
+Fl_Widget *Check_Button_Node::widget(int x, int y, int w, int h) {
+  return new Fl_Check_Button(x, y, w, h, "Button");
+}
+
+Check_Button_Node Check_Button_Node::prototype;
+
+
+// ---- Round Button ----
+
+void Round_Button_Node::ideal_size(int &w, int &h) {
+  auto layout = Fluid.proj.layout;
+  h = layout->labelsize + 8;
+  w = layout->labelsize * 4 + 8 + layout->labelsize; // make room for the symbol
+  fld::app::Snap_Action::better_size(w, h);
+}
+
+Fl_Widget *Round_Button_Node::widget(int x, int y, int w, int h) {
+  return new Fl_Round_Button(x, y, w, h, "Button");
+}
+
+Round_Button_Node Round_Button_Node::prototype;
+