I appreciate Dave's point about having pages from different projects open at the time in DW; I find it convenient for reference or copying code etc. However I think George's point makes good sense - and it can sometimes be confusing have different projects open at the same time. Switching projects is usually very quick and remembering the open pages etc. is great.
I suggested in a feature request an idea what would make it a lot more convenient - at least from my point of view - without any major changes to Wappler. It was a suggestion for a way to make switching between projects much quicker. But nobody voted for it. (I thought it was a good idea anyway.)