如何在弹出窗口关闭后直接使用组合框来正确设置焦点

When the user is selecting values from a combobox, if they choose a value, the "SelectionChanged" event fires and the new value is set and everything's fine. If, however, they decide not to change the value and click elsewhere on the UI (like a text box they want to edit), they have to click twice - the first click simply closes the combobox popup, and the next click will focus the element they wanted to activate on the first click.When the user is selecting values from a combob