The ONE thing that REALLY irks me about Xfce is that there are basically no "mile high mouse targets". Mile high mouse targets allow you to slam the mouse against the edge of the screen and click whatever button is there, thereby making the target object effectively infinite in height (this can be adapted to "mile wide" as well). If you've ever used a trackball, you should know what I'm referring to. But theres like a two pixel margin between the panel buttons and the edge, which, correct me if I'm wrong, has no purpose. M$ did this with the start button, and it is said that they "Snatched defeat from the jaws of victory". Other good mile high mouse target candidates would be the exit button, the scrollbar (right now I get a border grabber for these), and an option to remove the little "grabby things" (sorry) at the ends of the panel. This is one of the VERY few things that keep Xfce from being "just perfect". Reproducible: Always Steps to Reproduce: 1. 2. 3.
This has already been implmented in the 4.3 dev series. Both the panel and taskbar have no borders, and mashing the mouse up against the edge of the screen will still allow you to click the buttons.