TVirtualStringTree.ChangeDelay Property

Time which determines when the OnChange event should be triggered after the actual change event.

property ChangeDelay: Cardinal;

In order to accumulate many quick changes in the tree you can use this delay value to specify after which wait time the OnChange event should occur. A value of 0 means to trigger OnChange immediately after the change (usually a selection or focus change) happend. Any value > 0 will start a timer which then triggers OnChange. 

Note that there is the synchronous mode (started by BeginSynch) which effectively circumvents the change delay for the duration of the synchronous mode (stopped by EndSynch) regardless of the ChangeDelay setting.

TVirtualStringTree Class