custom textboxes in VB.Net - vb.net

Question

tldr - Made a subclass of Textbox, text looks screwy when it has focus. What's the proper way to handle it?
For my company's VB.Net application, I've been asked to make our textboxes behave like Google's textboxes, ie they need to have a blue-ish border around them when they have focus and a gray-ish border when they do not. I can already accomplish this by setting a textbox's BorderStyle to 'None', then drawing the appropriate rectangle within a form's Paint event. However, I have to do this for each and every single textbox that I use. And our application has quite a few of them. Needless to say, this is a pain and I'd rather have one piece of code that I can call upon.
So I figured that I have two options; I can either make a user control that contains a single textbox which uses the above method, or I can write my own class that inherits from the TextBox class and makes this behavior standard. I have elected to use the latter approach, and via overriding the OnPaint method I have achieved the desired behavior. But now I'm encountering some new pitfalls.
The main problem that I'm having is that text within the textbox is not rendered correctly when the textbox has focus. The text takes on a different font, appears bold, and highlighting looks wonky. If the textbox loses focus, the text looks correct. I suspect that I need to handle drawing for highlighted text differently, but I'm not sure what I need to do. Do I handle it in the OnPaint method or do I need to catch it somewhere else? Do I need to abandon this approach altogether and just make a user control?
Bonus question: for anyone with experience making custom textboxes, are there any tips or gotchas that I need to know about? This is my first time making a custom control, so I don't really know what all to expect.
edit: forgot to mention that I'm able to override OnPaint because I set the UserPaint flag to true. I'm guessing this was obvious, but I just want to be thorough.
edit2: Here's the class in its entirety.
Imports System.Drawing
Public Class MyCustomTextBox
Inherits TextBox
Public Sub New()
MyBase.New()
Me.BorderStyle = BorderStyle.None
SetStyle(ControlStyles.UserPaint, True)
End Sub
Protected Overrides Sub OnGotFocus(ByVal e As System.EventArgs)
'I want these textboxes to highlight all text by default
Me.SelectAll()
MyBase.OnGotFocus(e)
End Sub
Protected Overrides Sub OnLostFocus(ByVal e As System.EventArgs)
Me.SelectionLength = 0
MyBase.OnLostFocus(e)
End Sub
Protected Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)
Dim p As Pen = Nothing
'MyBase.OnPaint(e)
e.Graphics.FillRectangle(Brushes.White, Me.ClientRectangle)
If Me.Focused Then
p = New Pen(Brushes.CornflowerBlue)
Else
p = New Pen(Brushes.Gainsboro)
End If
e.Graphics.DrawRectangle(p, 0, 0, Me.ClientSize.Width - 1, Me.ClientSize.Height - 1)
e.Graphics.DrawString(Me.Text, Me.Font, New SolidBrush(Me.ForeColor), Me.ClientRectangle)
End Sub
End Class

Answer 1

As Hans mentioned, the TextBox doesn't even use the OnPaint method when it draws its text.
One way to do it is paint over the 3D border of the control in the WM_NCPAINT message. I won't claim it's completely flicker free:
Imports System.Runtime.InteropServices
Public Class TextBoxWithBorder
Inherits TextBox
Public Const WM_NCPAINT As Integer = &H85
<Flags()> _
Private Enum RedrawWindowFlags As UInteger
Invalidate = &H1
InternalPaint = &H2
[Erase] = &H4
Validate = &H8
NoInternalPaint = &H10
NoErase = &H20
NoChildren = &H40
AllChildren = &H80
UpdateNow = &H100
EraseNow = &H200
Frame = &H400
NoFrame = &H800
End Enum
<DllImport("User32.dll")> _
Public Shared Function GetWindowDC(ByVal hWnd As IntPtr) As IntPtr
End Function
<DllImport("user32.dll")> _
Private Shared Function ReleaseDC(ByVal hWnd As IntPtr, ByVal hDC As IntPtr) As Boolean
End Function
<DllImport("user32.dll")> _
Private Shared Function RedrawWindow(hWnd As IntPtr, lprcUpdate As IntPtr, hrgnUpdate As IntPtr, flags As RedrawWindowFlags) As Boolean
End Function
Public Sub New()
MyBase.BorderStyle = Windows.Forms.BorderStyle.Fixed3D
End Sub
Protected Overrides Sub OnResize(e As System.EventArgs)
MyBase.OnResize(e)
RedrawWindow(Me.Handle, IntPtr.Zero, IntPtr.Zero, RedrawWindowFlags.Frame Or RedrawWindowFlags.UpdateNow Or RedrawWindowFlags.Invalidate)
End Sub
Protected Overrides Sub WndProc(ByRef m As Message)
MyBase.WndProc(m)
If m.Msg = WM_NCPAINT Then
Dim hDC As IntPtr = GetWindowDC(m.HWnd)
Using g As Graphics = Graphics.FromHdc(hDC)
If Me.Focused Then
g.DrawRectangle(Pens.CornflowerBlue, New Rectangle(0, 0, Me.Width - 1, Me.Height - 1))
Else
g.DrawRectangle(Pens.Gainsboro, New Rectangle(0, 0, Me.Width - 1, Me.Height - 1))
End If
g.DrawRectangle(SystemPens.Window, New Rectangle(1, 1, Me.Width - 3, Me.Height - 3))
End Using
ReleaseDC(m.HWnd, hDC)
End If
End Sub
End Class
I override the OnResize event to send the RedrawWindow message, which basically makes the control invalidate it's nonclient area.
Refactor as needed.