Question

I’ve created a form that’s maximized over the entire screen.

Within that form, and sized to fill the entire form, I’ve placed a panel with background color set to Red. The form’s TransparencyKey is set to Red.

Therefore, the Panel is like a “keyhole” – you can see the desktop that’s directly underneath it.

When the user clicks on the panel, OR, presses a key on the keyboard, I want to take action.

But, because the panel is completely transparent, when it is clicked or a key is pressed, nothing happens. If I make the panel non-transparent (setting it’s background color to Blue, for example), it does respond to clicks.

What’s the best way to get the panel to respond to clicks and keypresses?

Do I have to hook all mouse an keyboard events on the entire system or is there a simpler way?

Answer 1

I’ve discovered that I can use GetAsyncKeyState to respond to both keypresses and mouse clicks.

[DllImport("user32.dll")]
public static extern int GetAsyncKeyState(System.Windows.Forms.Keys vKey);

Then, I can call GetAsyncKeyState(Keys.LButton) and GetAsyncKeyState(Keys.Escape), for example. Much simpler than hooking all keyboard and mouse events.