WinForms.
Let's say we have a grid on the form with some cell editors (checkboxes, radio button groups). The form has a file menu. File -> Save. User visits a few cells in the grid, and clicks a checkbox in a cell, and, without touching anything else with the mouse and without touching the Tab key, clicks on the File menu and then clicks Save.
Inside the Save menuitem click handler, is it possible to determine which checkbox in the grid had focus immediately prior? That checkbox won't have lostfocus yet because a menu choice doesn't cause its lostfocus event to fire.