Here is what is happening:
When Designer starts up it looks at all the patterns in the CarveWright folder (and recursively ALL sub-folders you have created there)
On Windows Vista, 7, and 8: C:\Users\<username>\CarveWright
On Windows Xp: C:\Documents and Settings\<username>\CarveWright
On MacOS X: /Users/<username>/Library/CarveWright
It generates a thumbnail for each pattern, these appear in the Pattern List.
Each Carving you place can have one or more thumbnail images created for it also, these appear in the Carving List.
Each font installed gets a sample text thumbnail, these appear in the Text Editor dialog.
There are several other ways images can be generated but they tend not to grow the longer you use the program, unlike the 3 cases above.
Each of these thumbnails uses one (or more) of a limited resource in Windows called a GDI Handle.
You can see how many a program uses with the Windows Task Manager.
With Task Manager open select: View>Select Columns... and check the GDI Objects box.
The limit is 10000 by default, and if a program exceeds that Windows will kill it.
The limit can be changed with a registry hack, but may make Windows unstable/unusable.
Mark Anderson
CarveWright (10/28/2008 - 6/18/2014)