a few err->errx since we don't have error messages here; from Tiago Cunha
For clients that support WM_TAKE_FOCUS in their WM_PROTOCOLS property, send
a ClientMessage event.
I believe we redraw the border in too many cases; likely a leftover from
the cc->pwin days - don't redraw on every unhide, resize, and mouse
move/resize Expose event (note, all Expose events trigger a redraw
anyway).

Tested with some finicky X apps I could think of, though I'm sure others
will find more - if so, and they 'lose' the border, please report!
Using xu_btn_ungrab() buttons during client_leave doesn't work (error
BadValue) when the modifier is already AnyModifier .  Instead alter
xu_btn_ungrab() to ungrab AnyButton/AnyModifier and call it only when a
client is coming into focus in client_setactive(), instead of iterating
over ignore mods - matches how we handle key grabs.
revert 1.138 (WM_TAKE_FOCUS) for now
wrap key ungrab like btn ungrab, for it'll be used again
shuffle
A client_delete should behave differently depending on whether the
triggering event was unmap (with pending destroy) log destroy; we only
need to grab/ungrab the server lock, set WithdrawnState and
XRemoveFromSaveSet clients coming from an unmap event - doing so for
clients coming from destroy are already gone, hence we generate errors.