Add "Floating Window Mode"

A simple borderless window floating on desktop. Window can be resized and moved by dragging. It also has some minimalistic controls showing on top of the video when cursor is hovering over it.\n\n This was a feature originally requested by @zahid1905.

clapper_src/revealers.js

@@ -190,6 +190,15 @@ class ClapperRevealerBottom extends CustomRevealer
         this.revealerBox.remove(widget);
     }
 
+    setFloatingClass(isFloating)
+    {
+        if(isFloating === this.revealerBox.has_css_class('floatingcontrols'))
+            return;
+
+        let action = (isFloating) ? 'add' : 'remove';
+        this.revealerBox[`${action}_css_class`]('floatingcontrols');
+    }
+
     set_visible(isVisible)
     {
         let isChange = super.set_visible(isVisible);