Close Multiple tabs!

Either the instructions are wrong or this addon jsut doesnt do its job as intended. I got a ton of tabs open, like over 1000, so closing many of them at once is needed. so say I wanna close the tabs 79 to 156, so basically a range of tabs right from the middle. according to instructions I first go to tab 79, click the aaddon icon once, then go to tab 156, click the icon again. now waiting, it starts to close tabs. you woul expect it to close tabs 79-156, right? but in my case many more tabs are closed. basically all the tabs from 1-156 are gone, not just the ones I intended! I cant say for certain if it always closes all tabs to the left or if it misbheaves slightly differently but fact is that it closed a ton of tabs outside the range I intended. the first time this closed MANY important tabs with no chance of recovery (cause firefox only memorizes like the last 7 closed tabs or so). this time, I had some tab session memorizer addon ready and thought of trying it again. but this adodn here still has that issue and is therefor unusable as it is! :-(