When the user clicks on an iconized (minimized) form in the taskbar, Windows sends that form a WM_QUERYOPEN message, and inspects the value returned to the operating system. If this value is zero, the operation is canceled.
Using subclassing you can therefore determine when a form is about to be restored, and you can also refuse to restore it by returning 0. Here is a code snippet that does the trick:
' REQUIRES THE MSGHOOK.DLL COMPONENT'' you can omit the following constant definition, ' because it is contained in the MsgHook type libraryConst WM_QUERYOPEN = &H13Dim WithEvents FormHook As MsgHookPrivate Sub Form_Load() ' start form subclassing Set FormHook = New MsgHook FormHook.StartSubclass hWndEnd SubPrivate Sub FormHook_AfterMessage(ByVal uMsg As Long, ByVal wParam As Long, _ ByVal lParam As Long, retValue As Long) If uMsg = WM_QUERYOPEN Then ' The iconized form is being restored. ' ... ' Uncomment the next line to prevent the window from being restored. ' retValue = False End IfEnd Sub