It's because you're making the buttons appear and disappear. When you move your mouse over them, your mouse "leaves" the form window and enters the button window, causing your `Form2_MouseLeave` method to execute, causing your buttons to become invisible. This causes your mouse to "enter" the form window, causing `Form2_MouseEnter` … Read More
Edited by ddanbe: addition
Edited by tanatos.daniel: I had to add something more.
Edited by tanatos.daniel