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Add to open/save dialogs new place. It will be created, when saving file by save dialog first time (for app fileplace). It will be created, when saving file with given mime type by save dialog first time (when first time selecting some mime type from dropdown menu).

User could select this place from places menu of save/open dialogs. Additionally, each place will contains empty file named blank by default.
Why? Because many users have problems with navigate and remember whereas he/she saves file. Idea isn't new - there's old idea about tagging files and search it by tag, but it was never realized. My idea is simpler.

Imagine I click file/save as. Save dialog appear. I click Application Document place and place enter, so blank file will be override. To open file, I click file/open. Now I click Application Document and click black twice.
Very simple.