In previous versions of Xfce, xfcalendar would pop up just above the panel when you click the clock, and just below the taskbar when you click it there. As of 4.2.2, clicking the clock ALWAYS brings up the calendar at the top of the screen. Reproducible: Always Steps to Reproduce: 1. Ensure you have Xfce Clock in the panel. 2. Single-click the clock. Actual Results: By default, the calendar pops up at the top-right of the screen, just below the taskbar. Expected Results: Appear where clicked; just above the clock when clicked, just below the taskbar if the system tray is present in the taskbar and the calendar is clicked. This is 4.2.0 behavior. My panel is on the primary (left) monitor, all the way at the bottom on the far-right in a horizontal configuration. Xfce Clock is the last item on the panel, closest to the right edge of the screen. A workaround exists, but it's a pain to implement. Take the calendar out of compact mode and turn off monitor border snapping and window snapping. Position the calendar in such a way that it is where you want it when it pops up in compact mode (you'll need to switch back and forth from normal to compact to get the exact position), then click the clock to hide the calendar. Next time the clock is clicked, the window position is remembered and it pops up in the same place.
This is how it works in 4.2.2 It starts as default position 0, 0 as you describe and remember position where you set it. If you are using xfwm4 window manager, you can also move the window by pressing <alt> and left button. You only need to do this once. Anyway it works as planned.
Moving all bugs to new Orage product.