Coalesce wxEVT_TEXT events in wxGTK wxTextCtrl and wxComboBox

For consistency with the other platforms, coalesce multiple wxEVT_TEXT
events resulting from a single user action into a single one in wxGTK
too. For example, when pressing a key in a control with some text
selected, wxGTK previously generated 2 wxEVT_TEXT events: one
corresponding to the removal of the selection and another one to the
addition of the new text. Now only a single event with the new text is
generated, as in the other ports.

Doing this requires delaying sending wxEVT_TEXT until GTK itself ends
handling the key press, however we delay it as little as possible, so
hopefully this shouldn't have any visible effects at wx API level.

Closes #10050.

include/wx/gtk/textentry.h

@@ -15,6 +15,7 @@ typedef struct _GtkEditable GtkEditable;
 typedef struct _GtkEntry GtkEntry;
 
 class wxTextAutoCompleteData; // private class used only by wxTextEntry itself
+class wxTextCoalesceData;     // another private class
 
 // ----------------------------------------------------------------------------
 // wxTextEntry: roughly corresponds to GtkEditable
@@ -62,12 +63,16 @@ public:
     bool GTKEntryOnInsertText(const char* text);
     bool GTKIsUpperCase() const { return m_isUpperCase; }
 
-    // Called from "changed" signal handler for GtkEntry.
+    // Called from "changed" signal handler (or, possibly, slightly later, when
+    // coalescing several "changed" signals into a single event) for GtkEntry.
     //
     // By default just generates a wxEVT_TEXT, but overridden to do more things
     // in wxTextCtrl.
     virtual void GTKOnTextChanged() { SendTextUpdatedEvent(); }
 
+    // Helper functions only used internally.
+    wxTextCoalesceData* GTKGetCoalesceData() const { return m_coalesceData; }
+
 protected:
     // This method must be called from the derived class Create() to connect
     // the handlers for the clipboard (cut/copy/paste) events.
@@ -95,6 +100,12 @@ protected:
     // GtkEntry IM context.
     int GTKEntryIMFilterKeypress(GdkEventKey* event) const;
 
+    // If GTKEntryIMFilterKeypress() is not called (as multiline wxTextCtrl
+    // uses its own IM), call this method instead to still notify wxTextEntry
+    // about the key press events in the given widget.
+    void GTKEntryOnKeypress(GtkWidget* widget) const;
+
+
     static int GTKGetEntryTextLength(GtkEntry* entry);
 
     // Block/unblock the corresponding GTK signal.
@@ -124,6 +135,10 @@ private:
     // It needs to call our GetEntry() method.
     friend class wxTextAutoCompleteData;
 
+    // Data used for coalescing "changed" events resulting from a single user
+    // action.
+    mutable wxTextCoalesceData* m_coalesceData;
+
     bool m_isUpperCase;
 };