If you want to be able to access GridViewIndentCell, you have two options:
1.Edit the template of a GridViewRow and find the part IndentPresenter, set its Visibility property to Collapsed.
2.Create a simple implicit style that is targeted at GridViewIndentCell and set its Visibility property to Collapsed.
Also you can remove the default padding in HierarchicalChildPresenter in GridViewRow's template.
Attached is a sample approach that demonstrates these techniques.
Considering your second requirement, you may take a look at this forum thread
for a reference on the same issue.
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