Sets whether this is modal.
A modal popover will grab the keyboard focus on it when being displayed. Focus will wrap around within the popover. Clicking outside the popover area or pressing Esc will dismiss the popover.
Called this function on an already showing popup with a new autohide value different from the current one, will cause the popup to be hidden.
| this |
a `GtkPopover` |
| autohide |
true to dismiss the popover on outside clicks |