我使用的是最新版本的 Ubuntu，但无法正常运行xvkbd。我收到这些错误：
$ xvkbd
Warning: Cannot convert string "-*-lucidatypewriter-bold-r-*-*-12-*-*-*-*-*-iso8859-1" to type FontStruct
xvkbd: Mode_switch not available as a modifier
xvkbd: although ISO_Level3_Shift is used instead, AltGr may not work correctly
Warning: Cannot convert string "-*-lucida-bold-i-*-*-14-*-*-*-*-*-iso8859-1" to type FontStruct
xvkbd: Mode_switch not available as a modifier
xvkbd: although ISO_Level3_Shift is used instead, AltGr may not work correctly
我该如何解决这个问题？我正在尝试将其与xbindkeys.