How to open bitcoin source in IDE?
I can recommend the Qt Creator IDE or Xcode on OSX. The later has (since Xcode 8) problems auto-completing C++.

If you use Qt Creators IDE, you can also debug the Qt objects natively.

In Qt Creator, do the following:


Install all dependencies
git checkout https://github.com/bitcoin/bitcoin
./autogen.sh
./configure --enable-debug (maybe more)
Then, create new project in Qt-Creator "import project from existing 
source".
Go to project settings / run, select src/qt/bitcoin-qt (or src/bitcoin) as executable
Happy debugging / coding.