SAMPLE: Accelerators for File Manager Extensions

SUMMARY

File Manager extensions cannot directly use accelerators because extensions do not have their own message pump. File Manager pulls messages on behalf of the extensions, and does not load and translate extensions's accelerators.

Download XTENACCL.EXE, a self-extracting file, from the Microsoft Software Library (MSL) on the following services:

• Microsoft Download Service (MSDL)

        Dial (206) 936-6735 to connect to MSDL
        Download XTENACCL.EXE (size: 25879 bytes) 
  

• Internet (anonymous FTP)

        ftp ftp.microsoft.com
        Change to the \SOFTLIB\MSLFILES directory
        Get XTENACCL.EXE (size: 25879 bytes) 
  

MORE INFORMATION

XTENACCL installs a task-specific message hook (WH_GETMESSAGE) and calls TranslateAccelerator() on every WM_KEY and WM_KEYDOWN message. If an appropriate accelerator is found, TranslateAccelerator() passes a WM_COMMAND to the main window.

The main window of File Manager handles and processes the WM_COMMAND message passed to it by TranslateAccelerator(). However, File Manager does not know how to handle that message because wParam (containing menu IDs) is defined by the extension. To interpret the correct value, File Manager dynamically changes an extension's menu IDs to suit its own needs. Therefore, XTENACCL traps the WM_COMMAND message passed by TranslateAccelerator() and routes it to a child window of its own. The child window in turn processes the menu command.

To intercept the WM_COMMAND message, XTENACCL is using a second message hook that is of type WH_CALLWNDPROC. Because TranslateAccelerator() sends a WM_COMMAND instead of posting it, this second hook was needed.