Your comments

By default, for a file log, the file is preselected in the Files view. Why hide all the other files?

If it is about commits, just select the two commits to compare.

Disabling is not possible (and probably won't), but maybe the preferences option "Preselect 'Staged' if files are staged, even if a file without staged changes is selected" helps you. I also recommend you to select View | Separate Working Tree and Index.

> In all three cases the search will be performed within the files remained on previous step (as now it is shown in Files-panel).
In some cases, e.g. 2 selected commits in the Graph, one entry in the Files table could mean multiple files (file states). In which one to search?

Could you also please describe your usecase - why you need this feature?

Please be more precise what exactly you want to be searched for? Should all files of the selected commit/between selected both commits/local files (if the working tree node is selected) be searched? Or just the visible filtered files?

Please describe your exact usecase.

You can configure external tools in the preferences since multiple versions.