Style Side Panel disabled with mobile useragent string

[Anders Rostén]

Hi,

I'm running with a custom useragent string (iPhone and iPad) on Firefox on Windows for testing purposes.
When i do this the style side panel is not populated with styles from an element i inspect. The same happens in the developer edition in Firebug 3 alpha.

I suppose this is done for optimization purposes, but makes it impossible to use firebug for testing CSS in this scenario.
Are there any change this could be a toggle or is it already possible to disable/enable this feature?

Thanks
Anders

[Jan Honza Odvarko]

Can you provide a simple test case (a page, can be online) we could
use to reproduce the problem on our machines?

Honza

[Anders Rostén]

Sorry for the late reply.

The issue does not seem to be consistant enough to really be a bug, You dont need a test page, simply go to www.cnn.com inspect the logo and see the css properties in the style panel. Now set a custom useragent and refresh the page, the style panel is now empty - but not always.

If you change from one useragent to another it seem its always empty, but if swithing back and forth from the default us it works.

The ua string i am using is the following: "Mozilla/5.0 (iPhone; CPU iPhone OS 7_1_2 like Mac OS X) AppleWebKit/537.51.2 (KHTML like Gecko) Version/7.0 Mobile/11D257 Safari/9537.53"

I'm using the User Agent Switcher addon to change the useragent.

[Sebastian Zartner]

I can reproduce that using Firefox 35.0 + Firebug 2.0.7 + User Agent Switcher 0.7.3 on Win8.1. Especially when you cancel the page loading you'll see that the Style side panel stays empty.

Sebastian

[Anders Rostén]

Investigating this more i found out that the style panel is also empty / disabled while NOT using a custom ua string.

When i disable the User Agent Switcher addon the style panel works again, so this must be an incompatibility issue between the two addons.

Im running version 0.7.3 of User Agent Switcher as @Sebastian Zartner.

[Anders Rostén]

Hi Jan,

After many headaches trying to work around the empty style panel I think I have found the actual reason and it has nothing to do with useragent strings - atleast not directly.

On my site im using Microsoft SignalR which has a transport fallback to longpolling requests if the device do not support websockets. Because im testing back and forth between mobile and desktop devices, i have been running longpolling requests for desktop browsers also, and it seems this is what makes the style panel blank.

It seems weird there should be any connection between these two things, but when i set the transport method to websockets in SignalR my style panel works fine.

A twist is that if i run with longpolling and open my site in a tab the style panel is empty, but if i open another tab with the same page the style panel works - this is what have made it very diffecult to debug because the behavior is so erractic.

I'm still not entirely sure this is the actual cause, but it seems to work for me when not using longpolling requests. This could be SignalR related or a general longpolling issue, i have not tested this with anything else than SignalR.