Merge pull request #315 from markotoplak/limited-301

[FIX] Fix bold fonts on Qt5 on Macs (apply QTBUG-58610 fix only on Windows)

Author: janezd

i18n/si/msgs.jaml

@@ -365,6 +365,7 @@ application/application.py:
             -style: false
             styleHints: false
             setShowShortcutsInContextMenus: false
+            win32: false
             QMessageBox: false
         def `argumentParser`:
             -style: false

orangecanvas/application/application.py

@@ -151,7 +151,7 @@ def __init__(self, argv):
                 sh.setShowShortcutsInContextMenus(True)
         if QT_VERSION_INFO < (5, 15):  # QTBUG-61707
             macos_set_nswindow_tabbing(False)
-        if QT_VERSION_INFO < (6, 0):  # QTBUG-58610
+        if QT_VERSION_INFO < (6, 0) and sys.platform == "win32":  # QTBUG-58610
             # https://github.com/musescore/MuseScore/pull/5820
             QApplication.setFont(QApplication.font("QMessageBox"))
         self.configureStyle()