I'm new to QT and I'm trying to create a gui for some command line kernel that I have in c++.

I need to create some drag and drops for icons similar to what we see in those circuit composer/circuit simulators.

here is an example of an interface that looks exactly like what I want to do, it uses
https://streamable.com/6qb43v

So if we break it down to a list, the features I need are:
1- Add straight lines and remove them
2- add some single input gates/just some colored squares (drag and drop)
3- a separator
4- multiple input gates

Being fairly new, I would appreciate if someone can link me to the appropriate QT resources and tell the easiest approach to achieve this.

I'm assuming I need to create a Qframe, just add the + button inside. But, On mouse click action for the +, how do I draw a line in the qframe?

How do Make the drag and drop guided to specific area? I have only seen tutorials for drag and drop to a big rectangular area but not something that drops the items in specific places like the circuit composer I showed above.
Also How do I handle drawing the colored rectangles that I will drag from the toolbox on the black lines?

I apologize for the noob question, Hope someone can guide me a bit...
Thanks in advance