The system registers the system classes for all processes to use. Any process can use a system class at any time. Because the system registers these classes, a process cannot destroy them.
Each Win32-based application receives its own copy of the system classes. All 16-bit Windows-based applications in the same VDM share system classes, just as they do on 16-bit Windows.
The following table describes the system classes:
| Class | Description |
|---|---|
| Button | The class for a button. |
| ComboBox | The class for a combo box. |
| ComboLBox | The class for the list box contained in a combo box. |
| DDEMLEvent | Windows NT: The class for DDEML events. |
| Edit | The class for an edit control. |
| ListBox | The class for a list box. |
| MDIClient | The class for an MDI client window. |
| Message | Windows NT 5.0 and later: The class for a message-only window. |
| ScrollBar | The class for a scroll bar. |
| Static | The class for a static control. |
| #32768 | The class for a menu. |
| #32769 | The class for the desktop window. |
| #32770 | The class for a dialog box. |
| #32771 | The class for the task switch window. |
| #32772 | Windows NT: The class for icon titles. |
Windows 95 and Windows 98: The system registers the system classes when it starts.
Windows NT: The system registers the system classes for a process the first time one of its threads calls a User or a GDI function.