ipython/ipython — pull request #1681 by ivanov (2012-05-02 01:30:07+00:00)
Title: add qt config option to clear_on_kernel_restart

Previously, restarting a kernel in the qtconsole always cleared the
entire session. Since qtconsole has a %clear command, it makes sense to
allow users to decouple the two activities - the restarting of kernels,
and clear the console.

To test, run:

ipython qtconsole --IPythonWidget.clear_on_kernel_restart=False

Here's what it looks like when the user restarts the kernel on `In[3]`:

```
Python 2.6.5 (r265:79063, Apr 16 2010, 13:57:41)
Type "copyright", "credits" or "license" for more information.

IPython 0.13.dev -- An enhanced Interactive Python.
? -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help -> Python's own help system.
object? -> Details about 'object', use 'object??' for extra details.
%guiref -> A brief reference about the graphical user interface.

In [1]: 0x42
Out[1]: 66

In [2]: 042
Out[2]: 34

In [3]: # restarting kernel...
#------------------------------------------

In [1]:
```