Update VirtualStringTree header after a component property has changed - delphi

Question

I would like to create a component named TMyComp.
This component has associated following properties:
property VirtualStringTree: TVirtualStringTree and
property Columns: TMyCompColumns as a collection of items.
The columns from my component are the same with the header columns from associated VirtualStringTree.
What I would like to do, is to redraw at design-time the header text from VirtualStringTree when the caption is updated.
My problem is that I don't know how to trig the procedure RedrawVirtualStringTreeHeader because it's not known by class TMyCompColumns or even TMyCompColumnsItem.
TMyCompColumnsItem = class(TCollectionItem)
private
FCaption: String;
function GetPosition: Integer;
protected
function GetDisplayName: String; override;
procedure SetIndex(Value: Integer);
public
constructor Create(Collection: TCollection); override;
procedure Assign(Source: TPersistent); override;
published
property Caption: String read FCaption write FCaption;
end;
TMyCompColumns= class(TCollection)
private
FOwner: TComponent;
protected
function GetOwner: TPersistent; override;
function GetItem(Index: Integer): TMyCompColumnsItem;
procedure SetItem(Index: Integer; Value: TMyCompColumnsItem);
procedure Update(Item: TMyCompColumnsItem);
public
constructor Create(AOwner: TComponent);
function Add: TMyCompColumnsItem;
property Items[Index: Integer]: TMyCompColumnsItem read GetItem write SetItem;
end;
TMyComp = class(TComponent)
private
FColumns: TMyCompColumns;
FVirtualStringTree: TVirtualStringTree;
procedure SetMyCompColumns(const Value: TMyCompColumns);
protected
{ Protected declarations }
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
published
property Columns: TMyCompColumns read FColumns write SetMyCompColumns;
property VirtualStringTree: TVirtualStringTree read FVirtualStringTree write FVirtualStringTree;
end;
...
function TMyCompColumnsItem.GetDisplayName: String;
begin
Result:= FCaption;
RedrawVirtualStringTreeHeader; //<--- procedure not recognized!!!
end;
...
procedure TMyCompColumns.Update(Item: TMyCompColumnsItem);
begin
inherited;
//RedrawVirtualStringTreeHeader; ???or here
end;
procedure TMyComp.RedrawVirtualStringTreeHeader;
var
i: Integer;
begin
if Assigned(FVirtualStringTree) then
begin
FVirtualStringTree.Header.Options:= FVirtualStringTree.Header.Options + [hoVisible];
FVirtualStringTree.Header.Columns.Clear;
if FColumns.Count > 0 then
for i := 0 to FColumns.Count-1 do
with FVirtualStringTree.Header.Columns.Add do
begin
Text:= FColumns.Items[i].Caption;
//...
end;
end;
end;

Answer 1

After some searching, this is the answer:
The trigger of RedrawVirtualStringTreeHeader has been done through the FOwner inside of TMyCompColumns class.
procedure TMyCompColumns.Update(Item: TCollectionItem);
begin
inherited;
(FOwner as TMyComp).RedrawVirtualStringTreeHeader;
end;
I updated property Caption: String read FCaption write FCaption with write SetCaption and I add the procedure
procedure TMyCompColumnsItem.SetCaption(const Value: String);
begin
FCaption:= Value;
Changed(False); //---> this will trigger TMyCompColumns.Update
end;
In fact the secret was Changed(False); that trig the Update
Thanks also to open source of TVirtualStringTree component.