Thanks a million, arj0n! I didn't even know about that list of game variables in the manual/help! I'd chosen dark red as the speech colour within the interface, maybe yellow is the default highlight? Anyway, awesome--that's fixed that (and you've opened up a new world of possibilities).

When you say you have to click it twice, are you saying that absolutely nothing is happening after the first click?
Hullo, Khris!

Yeah, after clicking the option that's meant to close the dialogue, the lines for the characters are displayed as scripted, but then the dialogue options are back again. If you click the aforementioned option again it does actually close.
My intention is for cMalcolm to say his line, cJerrysHead to say his, and for the dialogue to be gone. I've also tried putting
return RUN_DIALOG_STOP_DIALOG; within the if statement in various places but it doesn't appear to make any difference.
@3
if (JerryOneQfive < 1)
{
cMalcolm.SayBubble("Please just go away!");
cJerrysHead.SayBubble("Hmm hmm hmm da da da...");
JerryOneQfive++;
return RUN_DIALOG_STOP_DIALOG;
}
stop
Thanks again, everyone!