Run sphinx-autobuild via tox -e docs-live[-src]

tox.ini

@@ -49,11 +49,10 @@ sphinx_args = -W --keep-going -j auto
 # -d: use tox's temp dir for caching
 sphinx_args_extra = {[docs]sphinx_args} -v -E -T -a -d {envtmpdir}/doctrees
 
-[testenv:docs{,-lint,-all}]
+[testenv:docs{,-lint,-all,-live,-live-src}]
 skip_install = True
 change_dir = docs
-deps =
-    ./core[docs]
+deps = ./core[docs]
 passenv =
     # On macOS M1, you need to manually set the location of the PyEnchant
     # library:
@@ -64,6 +63,8 @@ commands =
     lint : python -m sphinx {[docs]sphinx_args_extra} -b spelling . {[docs]build_dir}/spell
     lint : python -m sphinx {[docs]sphinx_args_extra} -b linkcheck . {[docs]build_dir}/links
     all  : python -m sphinx {[docs]sphinx_args_extra} -b html . {[docs]build_dir}/html
+    live-!src : sphinx-autobuild {[docs]sphinx_args} -b html . {[docs]build_dir}/html
+    live-src  : sphinx-autobuild {[docs]sphinx_args_extra} -b html . {[docs]build_dir}/html --watch ../core/src/toga/
 
 [testenv:package]
 skip_install = True