Blender Git Loki

Fix T83861: Snapping panel from shortcut dissapears after click

This simple change sets the call_panel operator's "keep_open" property
to True for the viewport snapping panel called with `ctrl-shift-tab`.
There are quite a few settings in this panel, it often makes sense to
change more than one of them at a time, especially because multiple
snap elements can be active at the same time.