It's a very simple feature request keyboard shortcut in Thunar. In Thunar double clicking into the right-hand-side pane on an empty area(viz not a file), triggers Thunar to move 1 folder level up, viz the same as Alt+↑ keyboard shortcut. It saves so much mouse movements, that once you tried it, you want it. Thanks
In a sense it's very natural as: * in the left pane(folder structure) double mouse click triggers to show sub-folder structure, * in the right pane(view) double mouse click triggers to move to parent folder. (Leave the possibility to also have action with single mouse click so has to associate for instance with "previous folder navigation")
If I get it right, you dont actually want to move something, you want thunar to navigate to the parent folder on double-click on an empty space. I think this could be very irritating. If you double click on a file, but you miss it, thunar could navigate to the parent folder by accident. As well it would not work for the detailed view, since there is only empty space on the very bottom (if at all) Besides that, I dont think that it is a good idea to trigger something by just clicking "somewhere". That's not very self-explaining / not expected behavior. Instead I would advice you to reconfigure the "Alt+ up" shortcut to something you can reach with the left hand, so that you dont need to let the mouse go. You tried "View --> Location Selector --> Pathbar Style " ? As well makes it easy to navigate to the parent folder.