In Mac OS, the top menu bar is placed above any window, causing the
timelines being opened at (0,0) appear under it in such a way that the
timeline title bar is not reachable by the mouse, making it hard to
move.
This simple solution opens the windows a bit away from the top left
corner, at (100,100).
Fixes: https://pm.bsc.es/gitlab/rarias/ovni/-/issues/180
