Drop-down arrow button asymmetrical

The Bug

Arrows for drop-down lists are asymmetrical in most cases (reproduced in special screen resolution). In some circumstances the correct symmetrical arrows are shown.

How to reproduce showing normal, symmetrical arrows

See the attached video for the following steps

1. In the launcher click "Settings". Also works in "Installations", "Skins" or "Patch notes" tabs (does not work in "Play" and "News")

2. Move cursor over or click any clickable buttons in the user interface there

3. The arrow button becomes symmetrical

The arrows become asymmetrical again when clicking the "Play" tab.