When a window becomes managed, explicitly set the current border width
to the default instead of relying on the default value of -1 to apply
the correct value.
Now that there are two different kinds of default borders, a border
width value of -1 is ambiguous. This can lead to different border widths
effectively being applied when the container changes from tiling to
floating, which is surprising behavior.
This commit extends behavior introduced in this commit to normal
borders:
7afe9cc78b
Explicitly set current border width when BS_PIXEL
fixes#1304
Floating windows already had their own border style, but the width was
the same for all windows.
The configuration directives 'new_window' and 'new_float' can now be
used simultaneously to have different border widths for floating and
tiled windows.
fixes#1244
