Image Changes after program closes

I'm the newbie at this stuff...I did a search but I'll apologize in advance if I'm repeating a question that has been previously answered. I have built a simple widget that finds a specific jpeg file and displays, via the associations with the Window's picture viewer, the image full screen by double clicking on it. In the mouse off state it has one image, in mouse over state it has a second but slightly different image. Once clicked the widget is then hidden by the Windows picture viewer. What I'm looking for is a way to then change the mouse off state image, and mouse over state image to a entirely new image, in this case a thumbnail, that shows that the widget has been clicked and the picture viewed. So how can I change the mouse off and mouse on state images based upon the widget having fulfilled its task? Is this even possible?