[gnome-shell/gnome-3-38] workspacesView: Fix off-by-one error

[Florian Müllner <fmuellner src gnome org>]

commit 07ef8c57a4372a01b6b0ac583cf1e89c479ae3f9
Author: Florian Müllner <fmuellner gnome org>
Date:   Fri Jan 8 02:14:42 2021 +0100

    workspacesView: Fix off-by-one error
    
    The scroll adjustment's upper value corresponds to the number of
    workspaces, not to the last workspace index. We want the latter
    when mirroring the layout in RTL locales, so subtract 1.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1598>
    (cherry picked from commit 9f0e7632a6e1cb94bb9bf71002d548a8cbb2d558)

 js/ui/workspacesView.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/js/ui/workspacesView.js b/js/ui/workspacesView.js
index 2cc8b04897..eba43ad46c 100644
--- a/js/ui/workspacesView.js
+++ b/js/ui/workspacesView.js
@@ -292,7 +292,7 @@ class WorkspacesView extends WorkspacesViewBase {
         const vertical = workspaceManager.layout_rows === -1;
         const rtl = this.text_direction === Clutter.TextDirection.RTL;
         const progress = vertical || !rtl
-            ? adj.value : adj.upper - adj.value;
+            ? adj.value : adj.upper - adj.value - 1;
 
         for (const ws of this._workspaces) {
             if (vertical)