If you are looking for the decompiler itself, visit https://github.com/jindrapetrik/jpexs-decompiler
NEW : We have got a new blog where we post some interesting SWF internals info.List of issues
#2045 Keep open tabs
Right now, when you have one tab open and try to open another, the first tab closes and a new one opens. This is quite inconvenient and you have to pin the tabs. I think that the best option would be to do it like in an IDE, when you can open several tabs without any problems.
The option you talk about would require a double click on the treeitem to open it in the new tab. Since in the SWF there are many kinds of objects, mostly graphics like images, shapes, sprites, I don't think users would like to double click (and open new tab) everytime they want to see a preview of a graphic item. If it would be a single click, then there would be many unwanted tabs opened and user will need to close each one of them.