Added support for customizable keyboard shortcuts. Keyboard shortcuts can be added in flat_layout.xml by adding <shortcut> tags around the desired clients (No changes regarding the other xml files because I'm not sure what they do exactly...). Keyboard shortcuts are parsed as strings using KeysConverter without much sophistication. Some keys won't work, and there's no error reporting. Here's on that does work: Ctrl+Alt+F12. Also, added additional code to prevent preview windows and overlays from being shown when alt+tabbing.

PreviewOverlay.cs

@@ -41,5 +41,15 @@ namespace PreviewToy
 
         }
 
+        protected override CreateParams CreateParams
+        {
+            get
+            {
+                var Params = base.CreateParams;
+                Params.ExStyle |= 0x80;
+                return Params;
+            }
+        }
+
     }
 }