fix issue, then it wasn't possible to remove functional blocks from
project using right click and popup menu.

The problem is that, PopupMenu was called using IDEFrame object and as
a result item in ProjectTree loosed focus and focus went to IDEFrame.
Therefore later functions couldn't detect which item in ProjectTree
was selected.

Beremiz's user manual
=====================

Contents:

.. toctree::
   :maxdepth: 2

   install
   start
   edit
   build
   connectors
   debug