I want to use the Paintbrush Tool in GIMP, but it does not apply paint in a consistent manner.
Often the paint is applied very lightly, sometimes even hard to notice, or not at all (no Undo option becomes available). Sometimes there is a large difference in how heavily paint is applied in the area of the initial click VS the remainder of the area spanned by the cursor motion, occasionally even to the extent that the cursor-spanned area isn't affected at all. Sometimes these states of behavior self-correct or can be corrected by fiddling with arbitrary buttons (such as by changing tools and changing back). I often get an even lighter application of paint if I have a large number of images (such as 25) open simultaneously (which is actually something I want to do).
When I am getting at least some application of paint, even when I click, then Undo, then click again without moving the Paintbrush at all, the two clicks can yield two different results. Interestingly, this is not the case when I click, then Undo, then Redo, so the action history must be storing the results of my actions, not just my actions themselves.
This does not seem to be an issue with settings. Multiple times I have tried deleting /AppData/Roaming/GIMP before opening the program, and then I just pick a foreground color, set the Paintbrush Tool to some manageable Size and max Hardness, and already get an unpredictable application.
It also does not seem to be a hardware resource issue. I have 8 GB RAM on the computer I'm using, and even with over 20 images open, the GIMP Dashboard clocked me at around 1% CPU and 11% RAM usage. I am on Windows 7.
