in SLOT: determine which signal sent the signal?

[jacek]

It looks like you need more than one slot.

Slots should be implemented in such way that they don't need to know what signal was sent and who sent it. Otherwise you get tight coupling. "Do X or Y, depending on what happened" isn't a good way to code a slot. You should create two separate slots: "do X" and "do Y". This way you can decide what actions should be taken simply by establishing connections.