Enable reaching the Viewer's About dialog close button in small windows

I have no clue why it suddenly works without also setting the height to a fixed value. It just works in Chromium/Firefox on Linux and IE10 (though seems ODPs are not loaded there, guess nobody cared for IE recently, different construction area still...). So I feel like pushing this into master ;)
Anyone with more insight can also explain this?

Rekonq and Safari show the dialog left-aligned to the window, but no regression here. Also with Sarafi on the iPad here at least the old ViewerJS on viewerjs.org is not correctly working anyway (and another different construction area, to be visited independently).