But you're selecting the file in a file manager and then dragging it into your "file selector". That whole dialogue then becomes completely redundant because you might as well just drag that file into the application window without having to click "open".
> I get bitten at least a couple of times a week on Windows when I stupidly drag and drop the file I want to open
If you drag the file into the text area it will work as you wish. Or you could just drag the file into the application -- a lot of applications will support that and open the file without displaying the file open dialogue.