In this, the "normal" usage mode, a single XCALL XTREE causes the control object to be created and loaded with data. Unless the XTF_NOSEL flag is specified, the control will then receive the focus and wait for the user to perform an action that causes it to exit. On exit, unless the TXF_MODELESS flag is set, the control is deleted. If both XTF_NOSEL and XTF_MODELESS flags are set, the operation is essentially display—i.e. create the tree if necessary, configure it, load the specified data, display it, and return.
You may specify the XTREE control number (0-31) in XTR.CTLNO or or set it to -1, in which case the next available XTREE control control number will be used (and returned in XTR.CTLNO). If an XTREE control already exists with the specified number, the opcode will effectively be converted to XTROP_REPLACE, except that certain optimizations will be adjusted to work better for the case of a complete replacement of the tree contents—whereas XTROP_REPLACE is normally optimized for the case where only some of the data elements are changing.
