property TabOrder: TTabOrder; // published, inherited from TWinControl
TabOrder is a zero-based integer that determines the order in which the viewer is visited when the user repeatedly presses Tab. The lowest TabOrder in the same parent receives focus first, and Shift+Tab moves backwards through the sequence.
In a typical PDF reader window the viewer is usually given TabOrder := 0 so that pressing Tab after the form opens immediately enables keyboard navigation of the document. Toolbar buttons, sidebar lists and search boxes are then assigned higher values so they participate in the cycle without stealing focus on startup.
The property is meaningful only when TabStop is True — controls with TabStop = False are skipped by the tab cycle regardless of TabOrder. Re-assigning TabOrder at run-time renumbers the siblings automatically, just like in any other TWinControl.
TabStop.
// Give the viewer the first tab stop, then toolbar buttons, then the find box
procedure TForm1.FormCreate(Sender: TObject);
begin
PdfView1.TabStop := True;
PdfView1.TabOrder := 0;
btnZoomIn.TabOrder := 1;
btnZoomOut.TabOrder := 2;
edFind.TabOrder := 3;
end;