Images and math in tab headings broken in 2.0.0

[jmd-dk]

Describe the bug

Placing images and math in tab headings/titles does not work in version 2.0.0.

To Reproduce / Expected behavior

I'm not sure if it is (was) a deliberate feature, but prior to 2.0.0 one could have tabs like what is shown here. The Sphinx code generating this is of the form

.. tabs::

   .. tab:: |linux| :math:`\,\,` Linux

      Tab 1 text...

   .. tab:: |windows| :math:`\,\,` Windows

      Tab 2 text

where |linux| and |windows| are images defined as

.. |linux| image:: /_static/linux.png
   :height: 35px

.. |windows| image:: /_static/windows.png
   :height: 35px

I use :math: simply to produce some whitespace between the images and the titles.

With sphinx-tabs 2.0.0 we get the following: Neither the image nor the math is rendered. It's as though the RST-text isn't getting parsed but just used raw, as is.

Environment

• Python 3.9.1
• Sphinx 3.4.1
• Linux Mint 20

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[Daltz333]

I'm not sure if this is just intentionally not supported. Images in tab headings is non-trivial and won't look good for most cases. This may be where you might want to look into Sphinx-Panels navigation

[foster999]

Think this might be the same issue as #100. It sounds like v2.0.0 doesn't doesn't use nested parsing on the tab labels, so these directives are getting ignored. Shouldn't be too hard to add this back in.

The example with images linked above actually looks quite neat!