When developing for a tablet PC, how do I determine if the user clicked a mouse or a pen?

How do I check if the user clicked with a mouse or with a pen stylus on a C# control.

For eg. If the user clicks a text box with a pen button then I want an input panel to pop up but if he clicks with a mouse then it shouldn't. So how do I check whether he was using a mouse or a pen?

Edit: Using Windows Forms not WPF

From stackoverflow

• I don't really know too much about this, but I'd guess that if someone is using a stylus, then the mouseEnter, mouseExit (or whatever the equivalent is) events won't ever fire. If one does get fired, then you know that they're using a mouse.

  Nick Whaley : Those events still fire, it acts like a very fast move of the mouse.

• If you're using WPF then there's a whole host of Stylus events. E.g. UIElement.StylusDown.

  This has more details about how stylus and mouse events interact.

  If you're not using WPF, why not? :p

  Anirudh Saraf : Unfortunately I'm using Windows Form :( Any Suggestion for that?

• Have a look here.

  http://www.codeproject.com/KB/mobile/HandleMultiDigitizerInput.aspx

• I wrote an article for MSDN that never got published, I guess because Tablet PC development fizzled out by the time I got it to them. But it described how to do this. Long story short, you'll want the GetMessageExtraInfo API. Here's the definitions:

  // [DllImport( "user32.dll" )]
  // private static extern uint GetMessageExtraInfo( );
  
  uint extra = GetMessageExtraInfo();
  bool isPen = ( ( extra &  0xFFFFFF00 ) == 0xFF515700 );
  

  Email me at my first name at Einstein Tech dot net if you want me to send you the article.

  Anirudh Saraf : Thanks! Works like a charm.

  Anirudh Saraf : found a link to a MSDN article which explains why the above works, along with other info. http://msdn.microsoft.com/en-us/library/ms703320.aspx