Xrandr support detects default screen resolution instead of current

[vvjcarter]

when using the XRANDR support for detecting screensize the default screensize is used instead of the actual screensize. Function XRRSizes is used and first returned result is taken as the screen size (in GUI_X11:135, manpage for XRANDR(3) states that the first item in the list is the default size. Iam not knowledgable in Xrandr enough to see from a look at the manpage how to get the current config.