OK, I figured it out

When resizing the frame in meta_window_move_resize_internal() it is assumed that shaded windows don't have any bottom border:

  if (window->shaded)
    new_h = borders.total.top;

However, when calculating the frame borders in meta_frame_layout_get_border(), only the visible border is forced to 0 (with the result that a "full" invisible border is added).

So we got two possibilities for fixing it:

 1) Change the above code to

    if (window->shaded)
       new_h = borders.total.top + borders.total.bottom;

 2) Also enforce an invisible bottom border of 0 for shaded windows

Any preferences? For no particular reason I slightly prefer the second one ...

Created attachment 196782 [details] [review]
frames: Don't add an invisible bottom border for shaded windows

Shaded windows shouldn't have an invisible border, and it also causes
rendering errors elsewhere.


<magcius> fmuellner, the first is the correct fix no matter what, but do invisible borders matter on shaded windows?
<magcius> fmuellner, that is, the fix could be "both"
<fmuellner> magcius: not sure i agree that with the first one being "correct"
<magcius> fmuellner, we need to take borders into account, whether they are 0 or not.
<fmuellner> magcius: i'd define shading windows as "reduce to title bar"
<fmuellner> magcius: e.g. only the top decoration
<magcius> OK.
<fmuellner> at least that's my interpretation of the mutter code
<magcius> right

Created attachment 196783 [details] [review]
theme: Don't add any bottom border to shaded windows

Shaded windows are assumed to be reduced to the titlebar: the
current code enforces a visible bottom border of 0 and only takes
the size of the title bar (+ invisible top border) into account
when resizing the frame. However, we still add an invisible border
at the bottom, which is than subtracted from the title bar, resulting
in shaded windows being cut off.
Fix by forcing both visible and invisable bottom borders to 0.

Review of attachment 196783 [details] [review]:

"invisable" in commit message

Attachment 196783 [details] pushed as 6087a71 - theme: Don't add any bottom border to shaded windows

(In reply to comment #4)
> "invisable" in commit message

Gah. Shouldn't write commit message that late ...

*** Bug 659858 has been marked as a duplicate of this bug. ***