Merge remote-tracking branch 'sunset/process-enter'

Fix wxTE_PROCESS_ENTER logic for wxMSW and wxGTK too.

See https://github.com/wxWidgets/wxWidgets/pull/1415

Closes #18273.

include/wx/gtk/textentry.h

@@ -114,6 +114,10 @@ protected:
     // currently.
     virtual void EnableTextChangedEvents(bool enable) wxOVERRIDE;
 
+    // Helper for wxTE_PROCESS_ENTER handling: activates the default button in
+    // the dialog containing this control if any.
+    bool ClickDefaultButtonIfPossible();
+
 private:
     // implement this to return the associated GtkEntry or another widget
     // implementing GtkEditable