According to this release, Safari is suppose to be supported
Support for open standards that provide choice and flexibility: Lotus Quickr integrates with Microsoft Office 2003 and 2007, Microsoft Windows Explorer on Windows XP and Windows Vista, IBM Lotus Notes 7 and 8 (with planned support for Lotus Notes 6.5) and Lotus Sametime 7.5. Lotus Quickr supports Microsoft Internet Explorer, Firefox and Safari browsers, providing Web access from Windows, Linux, and Macintosh desktops.
And according to this post the problem dates back to QP7 and looked like there was a plan to fix it.
But, I'm still seeing only text editor for Safari on both Mac & PC. Is there a plan to fix this problem?