Dialog Control, Textboxes

Kinda 2 part question.

I was trying to handle an event for when left button is clicked on textbox in a dialog callback proc, how exacelty is this done, do I wait for the message WM_LBUTTONUP or something.
Also So given
BOOL CALLBACK HandleEventsHelper(HWND dhwnd,UINT message, WPARAM wParam, LPARAM lParam)

I pretty much understand what is sent in the UINT and WPARAM. So my question is what is sent in the LPARAM when clicking on textbox control. I cant find any documentation on this. Is it just garbage?



thanks :)

1) You'll probably have to subclass the edit control to intercept it's WM_LBUTTONUP message. The dialog procedure never receives it. A good starting point for learning about subclassing is the CallWindowProc function in MSDN.

2) The UINT parameter is the message id. Depending on the message the WPARAM and LPARAM parameters contain additional information. What this information is is specified in the documentation of the message. e.g. for WM_COMMAND (and therefore all notification messages) the high-order word (the upper 16 bit) of wParam are the notification code (e.g. EN_CHANGE) and the low-order word is the control id. lParam is the HWND of the control.