Firefox's Clear Recent History dialog's dimensions are not respected and you get a squished dialog which I oddly enough wasn't able to resize with the mouse.
I have seen this behaior too (though not in firefox, which I don't use). Using mod4+shift+space to switch the window out of floating mode seems to resize it to something usable.
Does #691 fix this for you?
Unfortunately, it doesn't. The window dimensions looks similar to the vertically large, horizontally small floating mpv (aka like a column), just not as high as the mpv window. Tested with sway version 0.6-107-g09670fc (2016-06-02, branch "master").
I get this in many places in Firefox. The easiest to reproduce is the window that pops when you click on the toolbar icon of the extension "uMatrix". I've also seen it many times already in other places too, just can't remember where.
As of today's build that's using https://github.com/Cloudef/wlc/commit/e3abf0b2f322b9d376ced452190cd4dd9f6fcb8a and https://github.com/SirCmpwn/sway/commit/ea0f1f3a7edf92537f74b70b520103bb38ff1411
the issue persists for me with Firefox, which now exclusively uses GTK+3, since GTK+2 support has been dropped.
Is this issue tracked in a different ticket, or should this one be re-opened?