Menu buttons in web interface jump down when expanded

When using the web interface for VLC media player 2.1.5 Rincewind on Fedora 20 (but may occur on all platforms where the web interface is available), the small menu buttons on the left move downwards a small distance when the menu is expanded. This sometimes causes the cursor to end up over the wrong menu item.

I have seen this with the following browsers:

Firefox 35.0 on Fedora 20
Firefox 35.0.1, Opera 27.0 and Internet Explorer 10 on Microsoft Windows 8.0

It does not occur in the mobile version of the web interface, because the menu buttons do not exist in that version.

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