This is an xfce4-panel modification I've come up with and have been using for some time now. It modifies the unhiding behaviour so that the panel will only show up, if there was either Ctrl or Alt key pressed while the cursor entered the sensitive area. This might be especially useful for laptops/nettops where screen resolution is very limited, but automatic unhiding seems too annoying when occurring accidentally. I'm not experienced enough to add this as a complete panel feature (being an option that can be selected in some menu and maybe a drop-down list of possible modifiers). If anyone finds this useful and knows how to add such feature in a proper way, please do so. Also, sorry for posting it here instead of the xfce-bugzilla - I just don't want to start a new account I probably would never use again. Reproducible: Always Patch should be self-explanatory. Other modifiers described at http://library.gnome.org/devel/gtk-tutorial/2.13/x2433.html should also be possible here.
Created attachment 186109 [details, diff] see the main enhancemen description Just patch the source, build, try out, and install if you like it!
please take things like this upstream