[gnome-shell] iconGrid: Only use page relative coords for orientation in getDropTarget

[Marge Bot <marge-bot src gnome org>]

commit f2db9b52c9113ed991a8786c88fa9ab9bccd6c74
Author: Sebastian Keller <skeller gnome org>
Date:   Sun Mar 14 17:32:26 2021 +0100

    iconGrid: Only use page relative coords for orientation in getDropTarget
    
    The x and y coordinates were both adjusted to be page relative, even
    though the icon grid can only scroll in one direction. This was leading
    to coordinates outside of the icon grid to be considered part of it and
    a wrong drop target to be chosen.
    
    Fixes https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/3779
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1767>

 js/ui/iconGrid.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/js/ui/iconGrid.js b/js/ui/iconGrid.js
index ddebc308e1..cdceb020df 100644
--- a/js/ui/iconGrid.js
+++ b/js/ui/iconGrid.js
@@ -1050,8 +1050,10 @@ var IconGridLayout = GObject.registerClass({
             page = swap(page, this._pages.length);
 
         // Page-relative coordinates from now on
-        x %= this._pageWidth;
-        y %= this._pageHeight;
+        if (this._orientation === Clutter.Orientation.HORIZONTAL)
+            x %= this._pageWidth;
+        else
+            y %= this._pageHeight;
 
         if (x < leftEmptySpace || y < topEmptySpace)
             return [null, DragLocation.INVALID];