Drawing artifact for sub-toolbar

[erikos]

- open Read

- hover over the View subtoolbar icon

result: subtoolbar opens

- move the mouse over the magnifier icon

result: palette for that icon opens and there is an artifact in the subtoolbar drawing, as well the palette does not look right

[erikos]

The artifact is that the sub-toolbar shrinks, therefore the grey border of the magnifier icon gets lost as well.

The difference in the palette is that the labels are not centered, they are to the left, see as well #3501 for this issue at another place.

[erikos]

A similar (maybe same) artifact can be seen in the bookmarks dialog in Read.

[erikos]

The easiest to reproduce this is:

- open Read with a pdf or any other handled data

- click on the 'add/remove' bookmarks icon (star)

- in the dialog hover over the cancel icon (x)

[godiard]

See comment in #3388