>>190

bool cancelRequested;

async button1_Click()
{
　button1.Enabled = false;
　button2.Enabled = true;

　cancelRequested = false;
　await Task.Run( DoWork );

　button1.Enabled = true;
　button2.Enabled = false;
}

button2_Click()
{
cancelRequested = true;
}

void DoWork()
{
　while( ! cancelRequested )
　{
　　;
　}
}