For example: I literally can't know how I can save a file using Gnome's dialogue in the general case, e.g. if the dialogue opens at /foo, and I navigate to /foo/bar using the dialogue, but then go back to /foo ("bar wasn't the right place after all"), I can't save the file there any more. "bar" will be selected. Clicking "Save" while a directory is selected will not save, but navigate instead. Now I'm in "bar" again. I go back to /foo and try to click something else, say a file. This changes the to-be-saved-file's name to the selection.
After I asked someone who uses Gnome as their main desktop they told me "that's easy: you just have to ctrl+click on the selected directory to de-select it, then you can save in the current directory".
That, my dear readers, is indeed unusable garbage.