16.4 Extension Messages

An extension can send the following window messages to retrieve relevant information from File Manager. File Manager is only guaranteed to respond correctly to messages sent from the FMExtensionProc function. For more information about these messages, see the Microsoft Windows Programmer's Reference, Volume 3.

Message Description

FM_GETDRIVEINFO File Manager returns drive information from the active window. An extension provides a pointer to an FMS_GETDRIVEINFO structure; File Manager fills the structure with drive information.
FM_GETFILESEL File Manager returns information about a selected file from the active File Manager window (either the directory window or the Search Results window). An extension provides a pointer to an FMS_GETFILESEL structure; File Manager fills the structure with file information.
FM_GETFILESELLFN Same as the FM_GETFILESEL message except that the selected file may have a long filename.
FM_GETFOCUS File Manager returns a value that identifies the type of window with input focus.
FM_GETSELCOUNT File Manager returns the count of selected files in the directory and Search Results windows.
FM_GETSELCOUNTLFN Same as the FM_GETSELCOUNT message except that the count includes files with long filenames.
FM_REFRESH_WINDOWS File Manager repaints either its active window or all of its windows. This message is similar to File Manager's Refresh command on the Window menu.
FM_RELOAD_EXTENSIONS File Manager reloads all extensions. First File Manager unloads all extensions, sending an FMEVENT_UNLOAD message to each exten-sion. Then it reloads the extensions, sending an FMEVENT_LOAD message to each extension. The FM_RELOAD_EXTENSIONS message allows an extension to uninstall itself by removing its setting from the WINFILE.INI file; this action causes File Manager to reload the remaining extensions. Other applications (for example, installation programs) can also post this message by calling the PostMessage function.