"Open in windows explorer" option grayed out in SharePoint on Office 365 using a mac. Trying to move a document appearing on the front page of the team site to a specific document library.
The "Open in Windows Explorer" option is not supported by Microsoft on Macs. This is primarily because Windows and Mac (among other operating systems) have different ways of handling those kinds of protocols. You may be able to use "Microsoft Document Connection" as a substitute though. Here is an article that may help: http://social.technet.microsoft.com/wiki/contents/articles/10527.sharepoint-work-with-documents-using-document-connection-for-mac-os.aspx
Of course it's greyed out, if you are in Mac OS you are not using Windows.
Download the document, then upload it to the second library. Once you have confirmed success, delete it from the first library.
You will lose some types of data on the file (like when it was created or any version history) by doing this.