[gnome-shell/gbsneto/fix-removing-pages] iconGrid: Properly remove pages

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit df35c3b8f733583b814827f28fa821b88e9ee4c1
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Thu Aug 13 17:58:51 2020 -0300

    iconGrid: Properly remove pages
    
    When the last item of an IconGridLayout page is removed,
    the page itself is removed too. However, the indexes of
    items of next pages are not updated, which mess up the
    layout manager state.
    
    Update the page index of the items at forward pages when
    removing a page.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1406

 js/ui/iconGrid.js | 8 ++++++++
 1 file changed, 8 insertions(+)
---
diff --git a/js/ui/iconGrid.js b/js/ui/iconGrid.js
index 2d3a17a626..df6f439c1f 100644
--- a/js/ui/iconGrid.js
+++ b/js/ui/iconGrid.js
@@ -468,6 +468,14 @@ var IconGridLayout = GObject.registerClass({
             this._unlinkItem(item);
         });
 
+        // Adjust the page indexes of items after this page
+        for (let i = pageIndex + 1; i < this._pages.length; i++) {
+            this._pages[i].children.forEach(item => {
+                const itemData = this._items.get(item);
+                itemData.pageIndex--;
+            });
+        }
+
         this._pages.splice(pageIndex, 1);
         this.emit('pages-changed');
     }