Common mistakes

Common mistakes

Table 3.5 lists the mistakes beginners make most often when creating Windows Forms applications.

Table 3.5. Common mistakes in Windows Forms applications

Problem	Cause	Fix
the code of button1_Click, textBox3_TextChanged handlers is hard to read	the controls were not renamed	change (Name) right after placing a control: convertButton
a compilation error after deleting a handler method	an event subscription remains in Designer.cs	clear the event in the Properties window (Reset)
FormatException in a button handler	double.Parse on a field's text without validation	TryParse, NumericUpDown, ErrorProvider
the window "freezes" during calculations	a long-running operation in a handler blocks the message loop	asynchronous async/await code (Topic 5)
a control with Dock = Fill covers the menu or status bar	wrong control order (Z-order)	Bring to Front for the control with Fill
the Cancel button does not close a form with an invalid field	Validating with e.Cancel = true does not release focus	CausesValidation = false for the Cancel button