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Hints & comments

Two ways to attach extra text to a cell: a tooltip on hover, or a persistent comment with a corner indicator and a popup balloon.

Overview

Mechanism API When to use
Hint Grid.Hints[col, row] or OnGetCellHint Tooltip on hover. Doesn't show in the cell itself.
Comment Grid.Comments[col, row] Persistent annotation. Shows a small indicator in the corner; balloon opens on hover or click.

Comments stay visible when the user moves away; hints disappear as soon as the cursor leaves the cell.

Hints (tooltips)

Static hint per cell

Pascal
Grid.Hints[1, 2] := 'This value was imported from the ERP system';

Dynamic hint via OnGetCellHint

For hints that depend on cell content:

Provide a dynamic hint per cellPascalC++
procedure TForm1.GridGetCellHint(Sender: TObject;
  ACell: TTMSFNCDataGridCellCoord; var AHint: string);
begin
  if ACell.Column = StatusColumn then
    AHint := 'Status: ' + Grid.Strings[ACell.Column, ACell.Row];
end;

void __fastcall TForm1::GridGetCellHint(TObject *Sender,
  const TTMSFNCDataGridCellCoord &ACell, System::UnicodeString &AHint)
{
  TTMSFNCDataGridCellCoord Cell = ACell;
  if (Cell.Column == StatusColumn)
    AHint = "Status: " + Grid->Strings[Cell.Column][Cell.Row];
}

When both the static Hints[] array and the event are set for the same cell, the event wins.

HTML in hints

The grid's HTML engine renders inside hints too:

Pascal
Grid.Hints[1, 2] :=
  '<B>Imported value</B><BR>' +
  '<FONT color="gcGray" size="10">Source: ERP, 2025-01-12</FONT>';

See HTML, anchors & highlighting for the full tag reference.

Comments

DataGrid cells showing corner comment indicators DataGrid cells showing corner comment indicators

Set a comment programmatically

Pascal
Grid.Comments[1, 3] := 'Reviewed by J. Smith on 2025-01-15';

A small indicator appears in the cell corner. Hovering the cell — or clicking the indicator — opens the comment balloon.

Set a comment via OnGetCellProperties

For dynamic comments that depend on cell content:

Set a comment dynamically per cellPascalC++
procedure TForm1.GridGetCellProperties(Sender: TObject;
  ACell: TTMSFNCDataGridCell);
begin
  if ACell.Column = ReviewColumn then
    ACell.Comment := 'Last reviewed: ' + DateToStr(Grid.Floats[ReviewColumn, ACell.Row]);
end;

void __fastcall TForm1::GridGetCellProperties(TObject *Sender,
  TTMSFNCDataGridCell *ACell)
{
  if (ACell->Column == ReviewColumn)
    ACell->Comment = "Last reviewed: " + DateToStr(Grid->Floats[ReviewColumn][ACell->Row]);
}

React to clicks on the indicator

Attach an anonymous method as the click handler:

React to comment indicator clicksPascalC++
procedure TForm1.GridGetCellProperties(Sender: TObject;
  ACell: TTMSFNCDataGridCell);
begin
  ACell.OnCommentIndicatorClick :=
    procedure(Sender: TObject)
    begin
      ShowMessage('Comment: ' + Grid.Comments[ACell.Column, ACell.Row]);
    end;
end;

// OnCommentIndicatorClick is a plain TNotifyEvent whose Sender is the cell itself,
// so a method handler replaces the anonymous procedure and reads the cell from Sender.
// OnCommentIndicatorClick is protected; a cracker class re-publishes it.
class TCellCracker : public TTMSFNCDataGridCell
{
public:
  __property OnCommentIndicatorClick;
};

void __fastcall TForm1::GridGetCellProperties(TObject *Sender,
  TTMSFNCDataGridCell *ACell)
{
  static_cast<TCellCracker*>(ACell)->OnCommentIndicatorClick = CommentIndicatorClick;
}

void __fastcall TForm1::CommentIndicatorClick(TObject *Sender)
{
  TTMSFNCDataGridCell *Cell = dynamic_cast<TTMSFNCDataGridCell*>(Sender);
  ShowMessage("Comment: " + Grid->Comments[Cell->Column][Cell->Row]);
}

Customise the comment balloon

The balloon control is exposed via Grid.Root.CommentPopup (on the renderer). Use it to change appearance, padding, or behaviour:

Pascal
Grid.Root.CommentPopup.FillColor   := gcLightYellow;
Grid.Root.CommentPopup.StrokeColor := gcGoldenrod;
  • Grid.Hints[col, row] — static hint text.
  • Grid.Comments[col, row] — static comment text.
  • OnGetCellHint — dynamic hint per cell.
  • OnGetCellProperties — set ACell.Comment and ACell.OnCommentIndicatorClick per cell.
  • Grid.CommentPopup — appearance of the comment balloon.

See also