A File Manager extension sends an FM_REFRESH_WINDOWS message to cause File Manager to repaint either its active window or all of its windows.
FM_REFRESH_WINDOWS wParam = (WPARAM) (BOOL) fRepaint; // repaint flag lParam = 0; // not used, must be zero
This message does not return a meaningful value.
File-system changes caused by an extension are automatically detected by File Manager. An extension should use this message only in situations where drive connections are made or canceled.