Expand an expandable item
int PtTreeExpand( PtWidget_t *tree, PtTreeItem_t *item, PhEvent_t *event );
This function expands the given subtree item. The tree argument must point to the tree that contains the item or can be NULL if the item doesn't belong to any tree.
If the item is in the tree, the tree's Pt_CB_TREE_STATE callback is invoked before the item is expanded. The event argument to this function is the event that's passed to the callback. Your callback function can prevent the expansion by setting the expand field in the callback structure to a nonzero value; zero means successful expansion.
The value assigned to the expand field in the callback structure, or zero if the item isn't in a tree or there's no Pt_CB_TREE_STATE callback that modifies the expand field.
PtTree, PtTreeCollapse(), PtTreeGetCurrent(), PtTreeGoto(), PtTreeItem_t, PtTreeShow()
PhEvent_t in the Photon Library Reference