Change Background Colour for Batch Queue Manager » Crop?

[Shaun of the Dead]

Hello!

Does anyone know if there's a way to change the default background / canvas colour when using the Batch Queue Manager with 'Crop' Base Tool applied?

My goal is to batch export photographs for Instagram. As we know, vertical images on Instagram often get auto-cropped weirdly. My hope is to use digiKam to reshape the images as a square with a white background (rather than its default black) so I can upload directly to Instagram without needing to do any intermediate (and slow) changing of canvas size with GIMP.

Suggestions anyone?

Thanks so much!