void __fastcall BeginUpdate();
Enables the TStrings object to track when the list of strings is changing.
BeginUpdate is called automatically by any property or method that changes the list of strings. Once the changes are complete, the property or method calls EndUpdate. Call BeginUpdate before directly modifying the strings in the list, and EndUpdate after. When implementing properties or methods that change the list in descendants of TStrings, call BeginUpdate before the changes are made, and EndUpdate when the changes are complete.
TStrings simply keeps track of when the list of strings is being changed. Some descendants of TStrings use this information to perform certain actions, such as telling a control to repaint, when updates are complete.