SelectAll causes freeze

[wysota]

You can probably use the canFetchMore() and fetchMore() feature of the model to do it without timers.

[Khal Drogo]

I use the treeview currently as a tableview, i.e. only top level items, no children.
I've never used canFetchMore() and fetchMore(), could you please explain a bit how it can help?

[wysota]

The view is irrelevant, it all happens inside the model. canFetchMore() is called to ask whether the model needs to update itself with new rows and fetchMore() does the update.

In your case canFetchMore() should return true if there are any pending rows and fetchMore() should append them to the model. I don't know if it will work (I never used those two methods), but it's worth to try. At worst you'll have to call those two methods yourself from within the timer.