Custom
The dialog will be displayed as a custom window shape using the custom mask file defined in
CustomMask.
Note: When some of these options are used, the controls that normally appear on the title bar-such as the "X"-shaped close button in the upper right corner-will not be available. Make sure you provide some other way for your users to exit from the dialog. (For example, you could have an "Exit" button somewhere on the dialog.) You can also exit the dialog using the Escape key, or ALT+F4.