VkSimpleWindow and VkWindow constructors both have the same form:
Unlike most other ObjectPak components, the VkSimpleWindow and VkWindow constructors do not require a parent widget as an argument: all ObjectPak windows are automatically created as children of the invisible shell created by your application's instance of VkApp. You must specify a name for your window. Optionally, you can also provide a standard Xt argument list that the constructor will use when creating the window's popup shell.
Every application has a main window. By default, the first window you create is treated as the main window. To specify a different window to use as the main window, use the VkApp::setMainWindow() function described in "Managing Top-Level Windows" .
Because the first window you create is by default the main window, the window class constructors also set some shell resources on the popup shell widget of that window. The constructors obtain the geometry of the invisible application shell created by VkApp and assign that geometry to the window's popup shell widget. The constructors also set the XmNargc and XmNargv resources on the popup shell to the values of VkApp::argc() and VkApp::argv() respectively. ("Application Data Access Functions" describes VkApp::argc() and VkApp::argv().)
Finally, for all windows, the window class constructors register a callback function to handle messages from the window manager. The default action of upon receiving a WM_DELETE_WINDOW message is to delete the window object. To change this behavior, override the handleWmDeleteMessage() member function as described in "Window Properties and Shell Resources" . The default action of upon receiving a WM_QUIT_APP message is to quit the application. To change this behavior, override the handleWmQuitMessage() member function as described in "Window Properties and Shell Resources".