xmms.xpm included in xmms-1.2.3-3.src.rpm is not installed, and the Icon entry in the desktop file is invalid.
Created attachment 5422 [details] patch for Icon entry in desktop file
Created attachment 5423 [details] patch libxmms/xmmsctrl.c and libxmms/formatter.c to use proper headers
Created attachment 5424 [details] patch for spec file
Will be in 1.2.4-7; thanks for the patches!