Often when I'm working and I split up my area into multiple panes, I sometimes like to keep certain panes open on certain files. Eg: one smaller pane will be CMakeLists.txt so that I can quickly add/remove files to the build.

When a file is opened, it opens to whichever pane has the cursor currently, and sometimes that means opening a file in a pane I mentally have reserved for something else. At this point I often 1) take a bit longer to find the file I just opened, since it isn't in the pane I expected. 2) have to switch the other pane back to CMakeLists.txt.

This, of course, isn't game-stopping workflow, but it could be a bit simpler if I could lock or pin certain files to certain panes.
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Perhaps, in an even more ambitious design, I could even specify file extension filters per pane. "This pane for *.h, This pane for *.cpp, This pane for *.ui, ..." and so on. That would be a really useful additional functionality.