Is it possible to have different models for different nodes in a tree panel? Consider a case like displaying employees within departments within companies. I want to display company, expanded to department, expanded to employee. At each level of node, I want some data associated with the node and have that available in the node when I do a cascadeBy() to traverse the tree, but the data is different for company vs. department vs. employee. It seems like the guide on the ExtJS doc site specifies one set of columns that applies to all nodes. Is there any way to specify different columns/models, each for a different class of node?