gtk2: Be more persistent trying to grab the keyboard.
We seem to get the 'visibility-notify' event before X is willing to
let us grab the keyboard, insisting that the target window is not
viewable (sic).
- gtk+-2/pinentry-gtk-2.c (grab_keyboard): Retry grabbing the
keyboard.
- GnuPG-bug-id: T2375
- Signed-off-by: Justus Winter <justus@g10code.com>