malposition of boxponters with non-widget source actors

Affected version

Arch / Gnome Shell 41.beta

Bug summary

The IBus candidate box is shifted twice the expected distance to the left.

Steps to reproduce

1. Install an input method like ibus-libpinyin or ibus-rime;
2. Run ibus-daemon -rdx in a terminal, then add the method from Settings > Keyboard > Input Sources;
3. Press Super+Space to enable the method, then type anything anywhere;

What happened

The candidate box appears at an unexpected place.

What did you expect to happen

The related MR should be !1903 (merged). And I got a temporary patch:

diff --git a/js/ui/boxpointer.js b/js/ui/boxpointer.js
index c7a8f92d0..987417646 100644
--- a/js/ui/boxpointer.js
+++ b/js/ui/boxpointer.js
@@ -470,8 +470,8 @@ var BoxPointer = GObject.registerClass({
             : sourceAllocation;
         let sourceTopLeft = this._sourceExtents.get_top_left();
         let sourceBottomRight = this._sourceExtents.get_bottom_right();
-        let sourceCenterX = sourceTopLeft.x + sourceContentBox.x1 + (sourceContentBox.x2 - sourceContentBox.x1) * this._sourceAlignment;
-        let sourceCenterY = sourceTopLeft.y + sourceContentBox.y1 + (sourceContentBox.y2 - sourceContentBox.y1) * this._sourceAlignment;
+        let sourceCenterX = sourceTopLeft.x + (sourceContentBox.x2 - sourceContentBox.x1) * this._sourceAlignment;
+        let sourceCenterY = sourceTopLeft.y + (sourceContentBox.y2 - sourceContentBox.y1) * this._sourceAlignment;
         let [, , natWidth, natHeight] = this.get_preferred_size();
 
         // We also want to keep it onscreen, and separated from the

sourceTopLeft.x(y) and sourceContextBox.x1(y) are the same in Clutter.Actor but sourceContextBox.x1(y) is always 0 in St.Widget with logged. So I simply removed sourceContextBox.x1(y).

Not sure if it's the right way to fix this problem, but it did fix that for me.

Anyway, hopefully this issue will be fixed quickly before the code freeze to reduce the impact on input method users. Thanks!

Relevant logs, screenshots, screencasts etc.