Linux distro: openSUSE Tumbleweed Plasma version: 5.9.4 KDE Frameworks version: 5.32 QT version: 5.7.1 Steps to reproduce: 1. Open a Dolphin window and navigate to some text file 2. Open Kedit or Kate (or any text editor using the KDE file chooser dialog) 3. Go to File > Open 4. Drag the file from the Dolphin window into the file chooser dialog Expected results: The file chooser dialog displays the directory containing the file and highlights it Actual results: The cursor gains a red "can't do that" icon below it, and nothing happens. You need to manually navigate to the location in the file chooser dialog, despite the fact that you already have the location open and visible in Dolphin. Notes: The GTK and MacOS file chooser dialogs support drag and drop in this manner, and it's very nice.
As a user, I would have expected a drop to a file dialog to move the file to the open folder. This might be the reason it was not implemented.
I'll note that the behavior works the way I'm proposing in Mac and GTK-based file choosers in Linux OSs. So if the user is at all familiar with those platforms, that might not be their assumption. If so, actually moving the file on a drag is semi-destructive. The whole drag-a-file-into-the-file-chooser-to-change-the-view-to-show-that-file is an incredible productivity booster in the Mac and GTK Linux worlds of the type that I sorely miss when I'm forced to use Windows.
Workaround: drag the file to the text box, not the file view, which pastes in the path and accomplishes the desired workflow. I still think dragging a file to the main file view should do the same, given that right now it does nothing and displays a "can't do that" cursor. Might as well have it do something useful and in the process match the behavior of the macOS and GTK file choosers.
*** This bug has been marked as a duplicate of bug 45154 ***