fix [#35713] Set Origin not waiting for user input.

Only activate search-box items on mouse-release,
Otherwise this gives odd behavior when using the operator-search popup since some tools expect the mouse buttons not to be held when activating which includes operators that have their own popup menus.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57422 954f8c5b-7b00-dc11-b283-0030488c597c