The CPL_DBLCLK message is sent to a Control Panel dynamic-link library (DLL) when the user double-clicks the icon of an application supported by the DLL.
lParam1
Specifies the application number. This number must be in the range zero through one less than the value returned in response to the CPL_GETCOUNT message (CPL_GETCOUNT – 1).
lParam2
Specifies the value loaded into the lData member for the application.
The Control Panel DLL returns zero if it processes this message successfully.
In response to this message, a Control Panel DLL should display the dialog box for the application.