INFO: Why RegisterClass() and CreateWindow() FailID: Q65257
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The RegisterClass() and CreateWindow() functions fail when the system
resources are used up. The percentage of free system resources
reflects the amount of available space in the USER and GDI heaps
within Windows. The smaller amount of free space is reported in the
Program Manager's About box because if either heap fills up, functions
fail.
Under Windows NT, the USER and GDI heap resources are practically
unlimited. Under Windows 95, the USER and GDI heap resources are greater
than Windows 3.1, but not as great as under Windows NT.
If the amount of free system resources remains low after the
application is exited, it is more likely that the GDI heap is filling.
The main reason for the GDI heap filling is that GDI objects that are
created by the application are not deleted or destroyed when they are
no longer needed, or when the program terminates. Windows does not
delete GDI objects (pens, brushes, fonts, regions, and bitmaps) when
the program exits. Objects must be properly deleted or destroyed.
NOTE: Win32-based applications cannot cause the USER or GDI heaps to
overflow when they terminate, because the system will release the resources
to maximize available resources.
The following are two situations that can cause the USER heap to get
full:
Keywords : kbNTOS kbGrpUser kbWinOS kbWndw
Version :
Platform :
Issue type : kbinfo
Last Reviewed: March 5, 1999