Preview in QtDesigner does not render QWebView URL

[eureka]

I have started Qt 5 app development in Ubuntu 14.04 and installed Qt 5.5 Creator, Qt 5.5 Designer, PyQt 5.5.1 and eric6 IDE.
I have two questions for starters.

(a) How do I Preview HTML content of QWebView object in container?
(b) How do I add Qt Creator to eric6 IDE (which has Qt Designer and Qt Linguist but not Qt Creator)

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More detail:

I created a small test app in Qt 5.5 Creator which loads a url (http://localhost) from QWebView object to display local HTML/CSS. QWebView URL has initial setting URL=http://localhost

Now when I click the Qt 5.5 Creator Run button the HTML is rendered correctly in a popup window .

The HTML output is only rendered when I click Run. I don't see any rendering in QMainWindow in Qt 5.5 Creator. I only see the (moveable) boundaries of the empty QWebView object in its container.

Now I switch to Qt 5.5 Designer and open mainwindow.ui.
And when I now go to Form > Preview ..
a popup window opens but there is no Preview of HTML content. Just a blank QWebView in the container.

I have read the docs ...

http://doc.qt.io/qt-5/qtdesigner-manual.html
http://doc.qt.io/qt-5/designer-quick-start.html

Is there some other configuration needed to Preview HTML content in QWebView object in Qt Designer?

This lack of Preview of QWebView HTML also applies when using Qt Designer launched from eric6 IDE. Is there a Qt 5.5 plugin for eric6 IDE so that I can open Qt Creator from eric6 IDE? Should I post this question to eric6 forum?