tooltip: Fix possible wrong placement
tooltip: Fix possible wrong placement

When showing a tooltip on the edge of a monitor, the tooltip could be wrongly
placed and be shown going from one monitor to the next.

This happened because the current_window wasn't set visible, and when it wasn't
the returned allocated size would be 1, hence wrong calculations.

Signed-off-by: Olivier Brunel <jjk@jjacky.com>

https://bugzilla.gnome.org/show_bug.cgi?id=698730

jadahl/gtk,Adamovskiy/gtk,jessevdk/gtk,davidgumberg/gtk,grubersjoe/adwaita,jigpu/gtk,jessevdk/gtk,jadahl/gtk,jessevdk/gtk,msteinert/gtk,jessevdk/gtk,msteinert/gtk,Lyude/gtk-,jessevdk/gtk,jadahl/gtk,alexlarsson/gtk,Adamovskiy/gtk,jadahl/gtk,Sidnioulz/SandboxGtk,alexlarsson/gtk,ahodesuka/gtk,alexlarsson/gtk,Adamovskiy/gtk,Lyude/gtk-,jadahl/gtk,ahodesuka/gtk,jadahl/gtk,jigpu/gtk,chergert/gtk,ahodesuka/gtk,ahodesuka/gtk,grubersjoe/adwaita,Lyude/gtk-,msteinert/gtk,ahodesuka/gtk,grubersjoe/adwaita,jessevdk/gtk,Lyude/gtk-,chergert/gtk,jigpu/gtk,chergert/gtk,davidgumberg/gtk,Adamovskiy/gtk,chergert/gtk,Sidnioulz/SandboxGtk,grubersjoe/adwaita,chergert/gtk,davidgumberg/gtk,Sidnioulz/SandboxGtk,alexlarsson/gtk,alexlarsson/gtk,ahodesuka/gtk,Lyude/gtk-,chergert/gtk,grubersjoe/adwaita,davidgumberg/gtk,davidgumberg/gtk,jigpu/gtk,davidgumberg/gtk,alexlarsson/gtk,jadahl/gtk,alexlarsson/gtk,jigpu/gtk,msteinert/gtk,ahodesuka/gtk,Sidnioulz/SandboxGtk,msteinert/gtk,Adamovskiy/gtk,Lyude/gtk-,Sidnioulz/SandboxGtk,Adamovskiy/gtk,Lyude/gtk-,ahodesuka/gtk,grubersjoe/adwaita,davidgumberg/gtk,Lyude/gtk-,Sidnioulz/SandboxGtk,Adamovskiy/gtk,jigpu/gtk,alexlarsson/gtk,davidgumberg/gtk,grubersjoe/adwaita,msteinert/gtk,Adamovskiy/gtk,jessevdk/gtk,chergert/gtk,jigpu/gtk,chergert/gtk,jigpu/gtk,grubersjoe/adwaita,jadahl/gtk