OK, let's summarize this:
- KDE4's "detect RandR (monitor) changes" service (part of kded4) calls upon XRRGetScreenResources() every 10 seconds (see Tormod's comment above, https://bugs.launchpad.net/ubuntu/+source/meta-kde/+bug/278471/comments/15). XRRGetScreenResources() is reportedly slow.
- R&R can then wreak havoc on the display, in that some drivers apparently (I cannot quote the source) disconnect an ENABLED output in order to check if another previously disconnected output has been hotplugged.
Say, on my i945GM-based laptop, I have DVI-D output (TMDS-1, external display) and LVDS (internal) enabled, and XRandR disables TMDS-1 to check for TV (no connectors available, neither on laptop nor docking station) or VGA presence.
- For some people including myself, disabling the TV output is a viable workaround.
See Bug #147073, specifically
- Some configuration or autodetection is b0rked and detects TV out when it shouldn't, see Bug #134365
Re the fix, I think avoiding XRRGetScreenResources (as gtk+2) did is only a workaround, not a solution. It would only hide the actual bug, namely something disconnecting CRTCs-in-use.