Today I realized that using the "FInd dialog", it is possible to search through all opened files.
I'd like to propose a new "scope"
All project files.
Normally I have a master document and several "included files". But only a few of the included files are actually open.
Now if i want to check for consistency "subtree" vs. "sub-tree" etc. It's quite a hassle to open all .tex files.
(Maybe, if a keyword is not even found, the file doesn't need to be displayed at all.)