cannot PREVIEW my text when writing a message for Support

cannot PREVIEW my text when writing a message for Support

On https://translatewiki.net/wiki/Special:Preferences#mw-prefsection-gadgets I have checked last Experiemntal [X] Mettre en évidence les sélecteurs CSS i18n.

When I write this message for support and click on the Preview button, the popup says the equivalent of 'you'll leave this page and loose your modifications' instead of showing the new formatting for possible correction (<= nok)

When I use the visual editor and ask the preview in a similare way for standard messages translations, the new formatting is well presented and the correction is possible (<= ok, normal behaviour).

Thanks.

ChristianW (talk)11:55, 28 November 2018