Fix wxComboCtrl popup behaviour under some Wayland compositors

We need to set the window type hint to COMBO in order to use a popup
window for it under Wayland and while not doing it seems to still work
with GNOME/mutter, it is required with the other compositors such as KDE
Plasma or Sway and doesn't seem to do any harm under GNOME, so do it
always and hope that it doesn't result in any problems with not
combobox-like popups.

This basically undoes 62d934a (Don't set HINT_COMBO as wxPopupWindow
is used for different windows as well, 2008-10-07).

See wxWidgets#23931, wxWidgets#23908.

Co-authored-by: Alex Shvartzkop <[email protected]>

(cherry picked from commit 5c0cc72)

Author: vadz

docs/changes.txt

@@ -287,6 +287,7 @@ wxGTK:
 - Give better error if EGL version is < 1.5 (Fabrice de Gans, #22325, #23855).
 - Fix hiding wxGLCanvas under Wayland (Joan Bruguera, #22580).
 - Fix page origin when printing in landscape (Alex Shvartzkop, #23860).
+- Fix wxComboCtrl popup behaviour under Wayland (Alex Shvartzkop, #23908).
 - Dramatically optimize adding many items to wxChoice (Ian McInerney, #23443).
 - Improve and document wxGLCanvas::CreateSurface() (Dan Gudmundsson, #23366).
 - Fix loading WebKit2 extension when using wxWebView (Scott Talbert, #23497).

src/gtk/popupwin.cpp

@@ -106,8 +106,12 @@ bool wxPopupWindow::Create( wxWindow *parent, int style )
     g_object_ref( m_widget );
 
     gtk_widget_set_name( m_widget, "wxPopupWindow" );
-    // wxPopupWindow is used for different windows as well
-    // gtk_window_set_type_hint( GTK_WINDOW(m_widget), GDK_WINDOW_TYPE_HINT_COMBO );
+
+    // While wxPopupWindow is used for different windows as well, we don't
+    // really know how is it going to be used but we do know that without the
+    // hint at all, it doesn't work correctly, at least under Wayland, where
+    // GTK only maps COMBO and {DROPDOWN,POPUP}_MENU to popups, so do set it.
+    gtk_window_set_type_hint( GTK_WINDOW(m_widget), GDK_WINDOW_TYPE_HINT_COMBO );
 
     // Popup windows can be created without parent, so handle this correctly.
     if (parent)