[gtk/wip/jimmac/tiled-resize-area-gtk4] Adwaita: control surface for resize tiled windows

[Jakub Steiner <jimmac src gnome org>]

commit edcd4c6207616ea97822b9a480ee2e07d6ce114c
Author: Jakub Steiner <jimmac gmail com>
Date:   Tue Feb 16 14:06:35 2021 +0100

    Adwaita: control surface for resize tiled windows
    
    - window resizing control area is implemented as where the shadows are drawn
    - create a 'fake' shadow for the tiled case to allow easier resizing of
      the tiled window ratio even if it's offset to the side of the border
    
    Fixes https://gitlab.gnome.org/GNOME/gtk/-/issues/3670

 gtk/theme/Adwaita/_common.scss | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)
---
diff --git a/gtk/theme/Adwaita/_common.scss b/gtk/theme/Adwaita/_common.scss
index ed26a7d290..6b4a734954 100644
--- a/gtk/theme/Adwaita/_common.scss
+++ b/gtk/theme/Adwaita/_common.scss
@@ -4117,9 +4117,11 @@ window {
   &.tiled-right,
   &.tiled-bottom {
    border-radius: 0;
-   box-shadow: 0 0 0 1px $_wm_border_backdrop;
-
-   &:backdrop { box-shadow: 0 0 0 1px $_wm_border_backdrop; }
+   box-shadow: 0 0 0 1px $_wm_border_backdrop,
+               0 0 0 20px transparent; //transparent control workaround -- #3670
+   }
+   &:backdrop { box-shadow: 0 0 0 1px $_wm_border_backdrop,
+                            0 0 0 20px transparent; // #3670
   }
 
   &.popup { box-shadow: none; }