Consider struts top/botton or left/right based on primary monitor size

Right now we require a strut to be as wide as the full screen to
create a TOP strut. This means that in a multi-monitor scenario (at
least if the primary monitor is leftmost) we will make the panel strut
be Meta.Side.LEFT due to the random side picking for corner objects.

This changes the width/height comparison to the primary monitor rather
than the screen to get this right. Also adds some docs about how
struts work in a multi-monitor situation.

https://bugzilla.gnome.org/show_bug.cgi?id=642881

diff --git a/js/ui/chrome.js b/js/ui/chrome.js
index f5e82920ea5a7c5fe2cd900ed4383944748e1c4b..4bad7c038a074549d001e58474589aaa98bc0669 100644 (file)
--- a/js/ui/chrome.js
+++ b/js/ui/chrome.js
@@ -363,41 +363,58 @@ Chrome.prototype = {
             if (!actorData.affectsStruts)
                 continue;
 
+            // Limit struts to the size of the screen
+            let x1 = Math.max(x, 0);
+            let x2 = Math.min(x + w, global.screen_width);
+            let y1 = Math.max(y, 0);
+            let y2 = Math.min(y + h, global.screen_height);
+
+            // NetWM struts are not really powerful enought to handle
+            // a multi-monitor scenario, they only describe what happens
+            // around the outer sides of the full display region. However
+            // it can describe a partial region along each side, so
+            // we can support having the struts only affect the
+            // primary monitor. This should be enough as we only have
+            // chrome affecting the struts on the primary monitor so
+            // far.
+            //
             // Metacity wants to know what side of the screen the
             // strut is considered to be attached to. If the actor is
             // only touching one edge, or is touching the entire
-            // width/height of one edge, then it's obvious which side
-            // to call it. If it's in a corner, we pick a side
+            // border of the primary monitor, then it's obvious which
+            // side to call it. If it's in a corner, we pick a side
             // arbitrarily. If it doesn't touch any edges, or it spans
             // the width/height across the middle of the screen, then
             // we don't create a strut for it at all.
             let side;
-            if (w >= global.screen_width) {
-                if (y <= 0)
+            let primary = this._primaryMonitor;
+            if (x1 <= primary.x && x2 >= primary.x + primary.width) {
+                if (y1 <= primary.y)
                     side = Meta.Side.TOP;
-                else if (y + h >= global.screen_height)
+                else if (y2 >= primary.y + primary.height)
                     side = Meta.Side.BOTTOM;
                 else
                     continue;
-            } else if (h >= global.screen_height) {
-                if (x <= 0)
+            } else if (y1 <= primary.y && y2 >= primary.y + primary.height) {
+                if (x1 <= 0)
                     side = Meta.Side.LEFT;
-                else if (x + w >= global.screen_width)
+                else if (x2 >= global.screen_width)
                     side = Meta.Side.RIGHT;
                 else
                     continue;
-            } else if (x <= 0)
+            } else if (x1 <= 0)
                 side = Meta.Side.LEFT;
-            else if (y <= 0)
+            else if (y1 <= 0)
                 side = Meta.Side.TOP;
-            else if (x + w >= global.screen_width)
+            else if (x2 >= global.screen_width)
                 side = Meta.Side.RIGHT;
-            else if (y + h >= global.screen_height)
+            else if (y2 >= global.screen_height)
                 side = Meta.Side.BOTTOM;
             else
                 continue;
 
-            let strut = new Meta.Strut({ rect: rect, side: side });
+            let strutRect = new Meta.Rectangle({ x: x1, y: y1, width: x2 - x1, height: y2 - y1});
+            let strut = new Meta.Strut({ rect: strutRect, side: side });
             struts.push(strut);
         }