[gtk/gtk-3-24: 3/5] win32 theme: Fix unfocused window buttons

[Luca Bacci <lbacci src gnome org>]

commit 2f30e12de72784390de6f3762387609283afc1b2
Author: Jaime Velasco Juan <jsagarribay gmail com>
Date:   Fri Oct 21 12:35:07 2016 +0100

    win32 theme: Fix unfocused window buttons

 gtk/theme/win32/gtk.css | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)
---
diff --git a/gtk/theme/win32/gtk.css b/gtk/theme/win32/gtk.css
index 218875e589..cd9b859c49 100644
--- a/gtk/theme/win32/gtk.css
+++ b/gtk/theme/win32/gtk.css
@@ -183,9 +183,18 @@ decoration:disabled {
   margin: -3px;
 }
 
+.titlebar .close image,
+.titlebar .maximize image,
+.titlebar .minimize image {
+    color: transparent;
+}
+
 .titlebar button.close {
     background-image: -gtk-win32-theme-part(window, 18, 1);
-    color: transparent;
+}
+
+.titlebar button.close:backdrop {
+    background-image: -gtk-win32-theme-part(window, 18, 5);
 }
 
 .titlebar button.close:hover {
@@ -202,7 +211,10 @@ decoration:disabled {
 
 .titlebar button.minimize {
     background-image: -gtk-win32-theme-part(window, 15, 1);
-    color: transparent;
+}
+
+.titlebar button.minimize:backdrop {
+    background-image: -gtk-win32-theme-part(window, 15, 5);
 }
 
 .titlebar button.minimize:hover {
@@ -219,7 +231,10 @@ decoration:disabled {
 
 .titlebar button.maximize {
     background-image: -gtk-win32-theme-part(window, 17, 1);
-    color: transparent;
+}
+
+.titlebar button.maximize:backdrop {
+    background-image: -gtk-win32-theme-part(window, 17, 5);
 }
 
 .titlebar button.maximize:hover {
@@ -238,6 +253,10 @@ decoration:disabled {
     background-image: -gtk-win32-theme-part(window, 21, 1);
 }
 
+.maximized .titlebar button.maximize:backdrop {
+    background-image: -gtk-win32-theme-part(window, 21, 5);
+}
+
 .maximized .titlebar button.maximize:hover {
     background-image: -gtk-win32-theme-part(window, 21, 2);
 }