You must have something in your code that is changing the focus. I created a simple project with 2 forms and 1 module. The first form has a text box and a timer control. When it loads it also loads form2 (form2.show). In the Timer control event it calls a function from the module. The module checks the text box on form1 and if it is not blank, adds the value to the list box on form2. When I do this form1 does not lose the focus so it is something specific in your code.