Just learn c #, want to capture the keyboard, the key combination stuck here, press CTRL + a, the result shows the CTRL + a, behind the letters are capitalized, according to a single button, display is a capital a lowercase, using the KeyDown event has occurred is not expected,

 private void textBox_KeyDown (object sender, KeyEventArgs e) 
{
Keystr=""; 
If (e.c. with our fabrication: ontrol) 
{
if (! Keystr. The Contains (Ctrl + "")) 
Keystr +="Ctrl +"; 
} 

Keystr +=e.K eyCode. ToString (); 

//MessageBox. Show (keystr); 
TextBox. Text=keystr; 
TextBox. Select (textBox Text Length, 0).//the cursor to the text finally 
TextBox. ScrollToCaret ();//scroll to the cursor 
}