Qt Creator plugin: how to insert foreign widgets from my plugin into QtQuick Designer

[mut]

Hello;

I'm building a plugin for Qt Quick Designer.

I was able to successfully create the basic Qt Creator plugin (http://doc.qt.digia.com/qtcreator-ex...st-plugin.html). Now I want to embed foreign widgets (W1, W2, W3, W4) from my plugin into QtQuick Designer itself. Obviously, I need to dig into QtQuick designer source code.

These foreign widgets are W1, W2, W3, W4, please see the attached file for their intended location.
W1: same nature as “Welcome”, “Design”, “Debug”, “Projects”, “Analyze”, “Help”. They will have the same parent.
W2: ToolBox Widget. It will be a selectable item in the “Library” dropdown list
W3: QGraphicsView. It will be a selectable item in the “main.qml” dropdown list
W4: QTabWidget: It will be a selectable item in the “Open Documents” dropdown list

My questions:
1) I have the entire source code of Qt Creator but I’m unable to locate the code for W1?
2) Where is the source code of the above refered dropdown lists? how these dropdown lists will interface with my code?
3) How to ensure that W2,W3, W4 occupy the same area as their parent and are resizable with them?
4) How do Qt Quick Designer code will call/interface with my code?

Thank you for your help.

Mut