[WIP] Switching syntax styles option

[mariacamilarg]

Now there is an option to change to a different syntax style that opens a new tab in the console with the selected color scheme:

[mariacamilarg]

@ccordoba12 @minrk I was doing this PR in order to find out if there was a way of changing the syntax_style without creating a new tab but that instead it got updated automatically in the same shell I've been working on.

The initial intention was inspired by spyder's spyder-ide/spyder#3908. However I was unable to do so. Do any of you know if this is possible? Or do I have to restart it and initialize it with the new config (as in this PR)?

[takluyver]

JupyterWidget has a _syntax_style_changed() method, which should be called automatically when syntax_style is set. So if you can get the active JupyterWidget instance, you should be able to do:

jupyter_widget.syntax_style = new_style

It might be that that doesn't work, though, if no-one's tested it before.

[takluyver]

We can use a pygments function to find the available styles:
http://pygments.org/docs/styles/#getting-a-list-of-available-styles

[mariacamilarg]

Oh this is way better! Thank you!

[wmvanvliet]

awesome!

[mariacamilarg]

JupyterWidget has a _syntax_style_changed() method, which should be called automatically when syntax_style is set. So if you can get the active JupyterWidget instance, you should be able to do: jupyter_widget.syntax_style = new_style

@takluyver I tried to do so before in another project (Spyder IDE) where I have the JupyterWidget instance:

The interesting thing was that the style_sheet was updated automatically (without restarting it or making a new tab). But the syntax style did not, it only got updated after I restarted Spyder.

This makes me think about your last line and that it maybe doesn't work. I tried to check both functions a bit but I couldn't figure out fast what could be wrong with the _syntax_style_changed() one.

[wmvanvliet]

Since this creates a new kernel, shouldn't this option do in the "Kernel" menu? Is there no way to change the pygments coloring of the currently running kernel? That would be super.

[ccordoba12]

@wmvanvliet, we'll fix that because we need it for Spyder.

[ccordoba12]

Closing in favor of #217.