You need to call this method any time you make changes to the attached FlexCelImport component, or when you want to change the sheet the control is displaying, in order to update the contents of the grid.

This is the OnChange event of the tab control on the XLSViewer demo. To gain a deeper undestanding of the whole picture, you should look at its code. 

FlexCelGrid only displays a sheet at a time. For this reason, the XLSViewer demo has a TFlexCelGrid inside an PageControl, and each time the user changes the tab it applies back the changes made on the current sheet and loads the new. 

procedure TMain.TabControlChange(Sender: TObject);
begin
  if DisableTabs then exit;
  Data.ApplySheet;
  FlexCelImport.ActiveSheet:= TabControl.TabIndex+1;
  Data.LoadSheet;
end;

TFlexCelGrid Methods