Use the same logic for closing dialogs as for handling Escape key.

Pressing "Esc" key closed the dialog with only wxID_OK button (but no
wxID_CANCEL one) by default but pressing the "close window" button only closed
it if wxID_CANCEL was present.

Fix this by using the same code in OnCloseWindow() as in OnCharHook(), after
extracting it into the new SendCloseButtonClickEvent() method.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65488 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/dialog.h

@@ -249,6 +249,13 @@ private:
     // can be used as our parent or NULL if it can't
     wxWindow *CheckIfCanBeUsedAsParent(wxWindow *parent) const;
 
+    // Helper of OnCharHook() and OnCloseWindow(): find the appropriate button
+    // for closing the dialog and send a click event for it.
+    //
+    // Return true if we found a button to close the dialog and "clicked" it or
+    // false otherwise.
+    bool SendCloseButtonClickEvent();
+
     // handle Esc key presses
     void OnCharHook(wxKeyEvent& event);