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.
wParam
Specifies whether File Manager repaints its active window or all of its windows. If this parameter is nonzero, File Manager repaints all of its windows. If this parameter is zero, File Manager repaints only its active window.
lParam
Not used.
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.