[Dillo-dev] How to use the tab or other keyboard keys to set foucs on web page links?

Hello All, I am using the Dillo on an embedded device for web browsing. Since this device does not support mouse or touchscreen, I have to use the keyboard(or some buttons). I found I cannot set the focus on these links using tab keys( Dillo 2.2-rc1). If there any key configuration settings to set the tab key? If not, I want to modify the source code to add this function, is there any example or related patches for reference? Thanks a lot! Yong