Hi, Yuni-

Can I ask what you want to edit about the ROI masks? There might be automatic tool ways of doing things (or perhaps different considerations altogether). In general, I don't know of many cases where ROI masks get edited.

Do you want to add or delete entire ROIs, and if so, according to what criterion (size?). If just voxels, what property do they have to earn removal?

By default in the AFNI GUI, the underlay dataset sets the grid for displaying data. You can overlay a low-res EPI on a high-res anatomical, but the EPI will be "regridded" automatically to match the anatomical.

I think this is what is restricting your choice of underlay in the "draw dataset" plugin-- I am guessing your cluster dataset is on a different grid than your anatomical. You could resample your anatomical to match the grid of your clusters, and then underlay it whilst drawing. To do this, you could use the following command where DSET_ANAT is your current anatomical and DSET_CLUST is your cluster dset:

3dresample \
    -input DSET_ANAT \
    -master DSET_CLUST \
    -prefix DSET_ANAT_RESAMPLED

Does that sort things out?

But again, it might be good to think about other ways of doing this procedure (and the goals of the editing).

--pt