HELP: Catch event between Textbox TextChange and Button Click events

Hi,

May I ask for an assistance in solving the current issue that I have.

Current Setup:

1. Textbox has textchanged event, in that event it populates a dropdown list.
2. When the Textbox is set to empty, it would delete the list in the dropdown list.
3. Button click would save the values of the textbox and dropdown selection.

Problem Scenario:

1. Set Textbox value to empty.
2. Cursor is still in the textbox
3. User clicks on the button
4, TextChanged event is fired.
5. Error message panel is not displayed

Required fix:

1. when Textbox value is empty
2. cursor is still in the textbox
3. user clicks on the button to validate that the textbox must not be empty.
4. Error Message panel is displayed.

Suggestion or workaround are welcome. I'm using C# btw.

Thanks!
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