I've tested this on two different systems (with TERM set to xterm-256color) and got the same result. Nothing in the config files seems relevant.
Is there a major difference in these terminal emulators that I'm not aware of?
Also, is any thorough documentation available for either of them? They seem to come with no man pages. I found the konsole handbook, but it is very basic.
WINDOWIDenvironment variable?WINDOWIDto determine that (or some heuristic that works less well). If you run a shell in Yakuake, doesecho $WINDOWIDshow anything?WINDOWIDto the same value thatxwininfofinds. But there is at least one different window, and while w3m sets aside space for images, they are not displayed.