Color flickering

[AndnixSH]

Border color is flickering when hovering

I'm using Windows 11 2h22

And can you make it possible to change color for FixedSingle? I need to use it for dark theme

[ConConner]

I myself had this issue as well. After a lot of online searching I was able to cobble together a fix that removes almost all of the flickering!

This works by instantly returning a IntPtr 1 as the Message.Result if certain messages get send.

Window Messages I was able to find that cause flickering:

• WM_MOUSEMOVE - 0x200
• WM_MOUSELEAVE - 0x2A3
• WM_SETFOCUS - 0x7
• WM_KILLFOCUS - 0x8

The updated WndProc override then looks like this:

//if (m.Msg == WM_MOUSEMOVE || m.Msg == WM_MOUSELEAVE ||
//      m.Msg == WM_SETFOCUS || m.Msg == WM_KILLFOCUS)

if (m.Msg == WM_MOUSEMOVE || m.Msg == WM_MOUSELEAVE)
{
      m.Result = (IntPtr)1;
}
else
{
      base.WndProc(ref m);
      if (m.Msg == WM_NCPAINT && BorderColor != Color.Transparent && 
          BorderStyle == System.Windows.Forms.BorderStyle.Fixed3D)
      {
          var hdc = GetWindowDC(this.Handle);
          using (var g = Graphics.FromHdcInternal(hdc))
          {
              using (var p = new Pen(BorderColor))
                  g.DrawRectangle(p, new Rectangle(0, 0, Width - 1, Height - 1));
              using (var b = new Pen(BackColor))
                  g.DrawRectangle(b, new Rectangle(1, 1, Width - 3, Height - 3));
          }
          ReleaseDC(this.Handle, hdc);
      }
}

I also added a second DrawRectangle to prevent a small white border in case of a darker background.
You will need to add the new Messages as constants as well at the top of your code:

const uint WM_MOUSELEAVE = 0x02A3;
const uint WM_MOUSEMOVE = 0x0200;
const uint WM_SETFOCUS = 0x0007;
const uint WM_KILLFOCUS = 0x0008;

Hopefully this helps!

[ConConner]

Well turns out I didnt test properly. Its not possible to edit the TextBox anymore with this "fix".

The problem are the WM_SETFOCUS and WM_KILLFOCUS, since some important code doesnt get run that way.
My knowledge ends here though, so I am not sure how to prevent this

[memoarfaa]

@AndnixSH
Can you try this fork
https://github.com/memoarfaa/TextBoxBorderColor