c# - How to set focus to a control in a Windows Forms application?

Question

In a Windows Forms application, when do I write the code to set the focus to a control both while the application is launched and subsequently after I call a function?

For instance, if I have a DropDownList, a TextBox and four buttons and I want the Focus to be set to the DropDownList, where do I write my code?

To set the focus to a particular control on application launch, I can set the tab index to that DropDown (with a minimum value, under the assumption TabStop property is set to True).

Now, if the user completes an operation (say, any of the Click Button Events) and then I update the DropDown and after that if I want to set the focus...I can do it as

MyDropDownList.Focus()

QUESTION

NB: The question is more about where, not how?

Answer 1

By far the simplest solution is to set the TabIndex property correctly so that your 'MyDropDownList' control has the lowest index. The next approach is to do it in the constructor. But you have to use Select(), the Focus() method cannot work yet because the control doesn't become visible until later.

Public Sub New()
    InitializeComponent()
    MyDropDownList.Select()
End Sub

Works in the Load event as well. Focus() starts working in the Shown event.