Prevent losing Focus in Textbox

Question

I am currently getting stuck with controlling components focus in C#.net. My goal is that preventing losing focus of Textbox A when "click" to another component (eg Textbox B or something). This "focus" mechanism will be kept except Textbox C or D ... is clicked.

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That might sound so weird but my situation is that Each of those rows A,C,D is a datarepeater item, and I only want to vertically move "focus" on the right column, not B column.

So, It is possible to do that in C# or I've got to find another control (not Data repeater). Any helps would be grateful.

I have edited your title... see [Should questions include "tags" in their title](http://meta.stackoverflow.com/questions/19190/should-questions-include-tags-in-their-titles), where the consensus is "no, they should not — Junaith, Jan 14 '15 at 08:14
What about attaching to the LostFocus event of your TextBox A, then check which Control currently has the focus and if it is TextBox B or any other 'not allowed' control simply call TextBoxA.Focus() again? — Tobias Breuer, Jan 14 '15 at 08:18
@Tobias that might cost expensive cause I have to iterate all of the control to find out which is currently being focused. — Kingcesc, Jan 14 '15 at 08:33
`var focusedControl = manyControls.FirstOrDefault(x => x.Focused)` will take less time than you can notice, for any number of controls lower than thousands, maybe even hundreds of thousands. I doubt you have this many controls. — SimpleVar, Jan 14 '15 at 08:50

score 0 · Accepted Answer · edited May 23 '17 at 11:58

You can use the Leave event of the TextBoxA along with a list that contains the controls that are allowed to acquire focus.

    [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Winapi)]
    internal static extern IntPtr GetFocus();

    private Control GetFocusedControl()
    {
        Control focusedControl = null;
        // To get hold of the focused control:
        IntPtr focusedHandle = GetFocus();
        if (focusedHandle != IntPtr.Zero)
            // Note that if the focused Control is not a .Net control, then this will return null.
            focusedControl = Control.FromHandle(focusedHandle);
        return focusedControl;
    }

    private void textBox3_Leave(object sender, EventArgs e)
    {
        //Any control that is allowed to acquire focus is just added to this array.
        Control[] allowedToAcquireFocusControls = { 
                 textBox1
            };

        Control focusedControl = GetFocusedControl();

        if (!allowedToAcquireFocusControls.Contains(focusedControl))
        {
            textBox3.Focus();
        }
    }

Reference: What is the preferred way to find focused control in WinForms app?

Prevent losing Focus in Textbox

1 Answers1