Although GPlates allows to modify and edit rotation files, most of the times I actually use TextMate as preferred text editor for modifications to individual moving plate rotation squences by hand. In addition, the upcoming GPlates rotation format change to the new *.GROT format (see PDF with the gory details here and a technical paper on the GPGIM in general here) requires a bit more metadata to be added to individual rotations. So I have decided cumbersome hand-editing can be replaced by code snippets and command completion using TextMate’s bundles and created a new GROT bundle for Textmate. The code is available on my BitBucket site as git repository (https://bitbucket.org/chhei/grot-bundle) for download, forking and public contributions.
Here are some screenshots of the new bundle in action with the Cobalt-Theme in Textmate: