After endless months of trial, tribulation and kicking the cat I have finally managed to get DRI working on my Dell laptop with Slack 9.1. Hooray! However, when I ran up the SearchAndRescue helicopter simulation for a trial run, my joy at not seeing the dreaded words 'extension DRI not found on display' (or whatever it was) was spoilt by this: "SAR needs an Alpha Channel - current alpha channel is 0 bits in size'.

My researches indicate that this is to do with X - a post on here tells me that 24 bit colour (which I am using) adds a further 8 bits of alpha channel (which I understand is transparency). Obviously mine is not adding it. Can anyone tell me why? Video card is ATI Rage Mobility P/M if that is the cause.

PS If anyone is struggling to do DRI on an ati Mach 64 card just shout and I will tell you what I did.

24 bit color contains no alpha channel. That's 16777216 colors you can display in that mode compared to the 65536 in 16 bit mode. 32 bit mode adds another 8 bits which are used for alpha transparency. Currently, X does not support true alpha transparency. So you're stuck in 24 bit color mode. Is SearchAndRescue a Linux binary, or are you running it through Wine/WineX (or the like)? As for your ATI card I don't know: I use Nvidia. Have you installed the ATI Linux drivers?