2 files changed, 4 insertions, 1 deletions
diff --git a/src/drivers/Wayland/Fl_Wayland_Window_Driver.H b/src/drivers/Wayland/Fl_Wayland_Window_Driver.H
index 192d82f5a..42967d6b1 100644
--- a/src/drivers/Wayland/Fl_Wayland_Window_Driver.H
+++ b/src/drivers/Wayland/Fl_Wayland_Window_Driver.H
@@ -56,6 +56,7 @@ private:
     Fl_Image* shape_; ///<  shape image
     cairo_pattern_t *mask_pattern_;
   } *shape_data_;
+  bool can_expand_outside_parent_; // specially to allow window docking (#987)
   cairo_rectangle_int_t *subRect_;   // makes sure subwindow remains inside its parent window
   static bool in_flush_; // useful for progressive window drawing
   Fl_Cursor standard_cursor_; // window's standard custom kind
@@ -143,6 +144,7 @@ public:
   static bool new_popup; // to support tall menu buttons
   bool process_menu_or_tooltip(struct wld_window *);
   static Fl_Window *previous_floatingtitle; // to support floating menuwindow w/ title
+  void allow_expand_outside_parent() FL_OVERRIDE { can_expand_outside_parent_ = true; }
 };
 
 
diff --git a/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx b/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx
index 904c878da..be0abf38e 100644
--- a/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx
+++ b/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx
@@ -70,6 +70,7 @@ Fl_Wayland_Window_Driver::Fl_Wayland_Window_Driver(Fl_Window *win) : Fl_Window_D
   gl_start_support_ = NULL;
   subRect_ = NULL;
   is_popup_window_ = false;
+  can_expand_outside_parent_ = false;
 }
 
 
@@ -1889,7 +1890,7 @@ static bool crect_equal(cairo_rectangle_int_t *to, cairo_rectangle_int_t *with)
 
 
 void Fl_Wayland_Window_Driver::checkSubwindowFrame() {
-  if (!pWindow->parent()) return;
+  if (!pWindow->parent() || can_expand_outside_parent_) return;
   // make sure this subwindow doesn't leak out of its parent window
   Fl_Window *from = pWindow, *parent;
   cairo_rectangle_int_t full = {0, 0, pWindow->w(), pWindow->h()}; // full subwindow area