Add Python 3.10 to tox.ini

qt/preferences_dialog.py

@@ -302,6 +302,7 @@ use the modifier key to drag the floating window around"
             setchecked(self.reference_bold_font, prefs.reference_bold_font)
             setchecked(self.tabs_default_pos, prefs.tabs_default_pos)
             setchecked(self.use_native_dialogs, prefs.use_native_dialogs)
+            if plat.ISWINDOWS:
                 setchecked(self.use_dark_style, prefs.use_dark_style)
             setchecked(
                 self.details_dialog_titlebar_enabled,
@@ -347,6 +348,7 @@ use the modifier key to drag the floating window around"
         prefs.tableFontSize = self.fontSizeSpinBox.value()
         prefs.tabs_default_pos = ischecked(self.tabs_default_pos)
         prefs.use_native_dialogs = ischecked(self.use_native_dialogs)
+        if plat.ISWINDOWS:
             prefs.use_dark_style = ischecked(self.use_dark_style)
         lang = self.supportedLanguages[self.languageComboBox.currentIndex()]
         oldlang = self.app.prefs.language

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py36,py37,py38,py39
+envlist = py36,py37,py38,py39,py310
 skipsdist = True
 skip_missing_interpreters = True