Picking cells inside polygon drawn with the mouse

Hi there,
I am developing an application based on acquiring a STL mesh with a laser line sensor. The mesh is used to plan a robot path to perform some operations based on an interaction with the user. I mean, once the mesh is acquired by the sensor it should appear on a graphical user interface where the user has to select with the mouse a region of the mesh where the robot should perform the operations.
So my questions are multiple:
-are there some examples available showing how to pick cells of a mesh inside a polygon drawn with a mouse? I would like to replicate what happens with software like Meshlab, where you select an area and you delete all the points of the area
-is vtk compatible with GUI libraries such as tkinter or Qt? I mean, the mesh should appear inside a canvas of a window.
Thanks a lot, sorry but I am new to VTK and I cannot find examples about this topic.

Anyone could help me, please?