Setting this property to true allows users to resize forms, click buttons, etc. while documents are being generated. This makes applications more responsive, and is necessary if you want to provide a "Cancel" button to stop the document generation (otherwise the user wouldn't be able to click the button until the generation is complete).

Setting this property to false will cause documents to generate slightly faster.

The code below implements "Generate" and "Cancel" buttons attached to a C1PrintDocument.

The "Generate" button checks whether the document is busy before starting to generate it. This is necessary because the user could click the "Generate" button several times in a row, before the document got a chance to finish generating. (Calling the C1MultiDocument.Generate method while the component is busy throws an exception.)

The "Cancel" button checks whether the document is currently generating, and sets the C1MultiDocument.Cancel property to true if it is.

_doc.DoEvents = true;
            
private void Generate_Click(object sender, EventArgs e)
{
   if (_doc.BusyState != BusyStateEnum.Ready)
       Console.WriteLine("Cannot generate now, document is busy");
   else 
       _doc.Generate();
}
private void Cancel_Click(object sender, EventArgs e) 
{
   if (_doc.BusyState != BusyStateEnum.Ready) 
       _doc.Cancel = true;
   else 
       Console.WriteLine("Document is not generating, nothing to cancel");
}

Reference

C1MultiDocument Class
C1MultiDocument Members