Sets a position func to position the popover.
In @func, you should set the height of the rectangle to the maximum height that the popover should be allowed to grow.
A function to call to position the popover, or %NULL to set the default.
closure data for @func
a destroy notify for @func_data
3.26
See Implementation
Sets a position func to position the popover.
In @func, you should set the height of the rectangle to the maximum height that the popover should be allowed to grow.