I need a GUI IDE or a GUI framework compatible with PyDev and Eclipse.
There is no Eclipse embedded GUI editor for any of the Python GUI frameworks, but it's not so bad. Do you really need for it to be integrated on Eclipse?
The closest you can get is may be use Jython and use some swing GUI editor.
Depending on the framework you want to use (GTK+/QT3/QT4/wxWidgets) you'll get to choose a graphical GUI editor.
I cannot spend time learning something cause the functionality is yet to be completed.
It doesn't matter what tool we give you, you are going to have to learn to use it.
I'm looking for very simple GUI for a simulation game.
If what you want is to develop is a game, you should take a look at PyGame (must read) and Cocos2D, although there a lot more others.