This example enables a CommandButton control whenever a TextBox control contains text. To try this example, paste the code into the Declarations section of a form with CommandButton and TextBox controls, and then press F5 and enter something into the text box.
Private Sub Form_Load ()
Text1.Text = "" ' Clear the text box.
Command1.Caption = "Save" ' Put caption on button.
End Sub
Private Sub Text1_Change ()
If Text1.Text = "" Then ' See if text box is empty.
Command1.Enabled = False ' Disable button.
Else
Command1.Enabled = True ' Enable button.
End If
End Sub