Hi,
In Painter IX (IX 9.1 and IX.5) custom brush variants are saved to the Painter IX User folder, not to the Painter IX application/program folder where the software was installed.
The Painter IX User folder is located here:
Mac - /Users/[User Name]/Library/Application Support/Corel/Painter IX/
Windows - Documents and Settings\[User Name]\Application Data\Corel\Painter IX
Painter IX automatically creates the .NIB and .STK files for each brush variant.
If you also see a .JPG file with the same name as the .XML brush variant file, it means the brush variant is a Captured Dab variant and uses that image to describe the shape and opacity of the brush dab.
Jinny Brown