Which IDE should I use when developing extensions?

I plan on making tilemap extension (not Tiled, OGMO or other open source level editor importer, mind you) for GD but I wonder which IDE should I use to develop it? I’d prefer if it would feature Delphi-like form designer so making tilemap editor window would be easy for me (I have pretty much idea how it would work behind scenes, such editor would save me trouble of positioning widgets in code which is always messy for me) and preferably with Delphi-like events/signals.

I’ve been using Code::Blocks for a long time, it has an integrated visual editor called wxSmith that can be used to generate dialogs for wxWidgets (the toolkit used by GD for the GUI).
Now I’ve switched to Sublime Text which is a really powerful, easy to use and efficient text editor for programmers. I still use Code::Blocks to modify the already existing dialogs, but new dialogs are now created using wxCrafter ( wxcrafter.codelite.org/ ) which is another complete visual editor for wxWidgets.
I prefer to separate the tools I’m using so that I do not rely on any IDE or specific tool.

All the C++ code of the extension and of the SDK of Game Develop are compiled using CMake: It is a powerful tool which can generate build files for a lot of system: You can ask it to generate makefiles or even Code::Blocks projects.
In any case, just read the documentation bundled with the SDK: There are pages explaining how to launch CMake (it even has nice screenshots) and how to compile extensions.