After updating to Chrome 37 today I noticed that modal dialogs in a Sitecore CMS 7.0 instance weren’t working. Turns out window.showModalDialog was deprecated in this release of Chrome, and it won’t be the only one:
Clients using older versions of Sitecore (7.2 and 7.1 are okay, 7.0 isn’t) with modern browsers (Chrome 37/Opera 24/Firefox ~32 or higher) will have problems using Sitecore as modals won’t show; instead they’ll just get a greyed out screen overlay.
What’s the fix?
- Stick to an older browser (but we don’t want this and it won’t stop those auto-updating browsers).
- Re-enable the feature in Chrome as mentioned here with an Enterprise Policy setting to re-enable showModalDialog (Chrome only and only until “May 2015” when it’ll be completely deprecated).
- Upgrade clients to the latest version of Sitecore (7.1+) which uses a different modal/dialog system
-  Opera Dev blog indicates other browsers to follow.
- Chrome 37 to disable showModalDialog by default.
- Chrome 37 adds support for <dialog> element as a replacement for showModalDialog.
- Why showModalDialog sucks.
Update: Thanks to @timhacker for finding out that Sitecore 7.1 is also okay.