Controlling designer appearance of double-buffered owner-drawn UserControl in C#/.NET 2.0

Question

I have an owner-drawn UserControl where I've implemented double-buffering. In order to get double-buffering to work without flicker, I have to override the OnPaintBackground event like so:

protected override void OnPaintBackground(PaintEventArgs e)
{
    // don't even have to do anything else
}

This works great at runtime. The problem is that when I have an instance of the control on a form at design time, it becomes a black hole that shows trails of whatever windows are dragged over it (because the override of the OnPaintBackground event also governs design-time appearance). It's just a cosmetic problem, but it's visually jarring and it always leads new developers on the project to assume something has gone horribly wrong.

Is there any way to have an overridden method like this not be overridden at design time, or is there another solution?

Answer 1

if (this.DesignMode)
{
    return;    //or call base.OnPaintBackground()
}

Answer 2

Steven Lowe's solution unfortunately cover all scenarios, espcially when user controls come into the picture.

The this.DesignMode flag is very deceptive. Its only scope is to check if the direct parent is within the designer.

For instance, if you have a Form A, and a UserControl B, in the designer:

• A.DesignMode is true when viewed in designer
• B.DesignMode is false when viewing A, but true when looking directly at B in the designer.

The solution to this is a special flag to check (sorry for the ugly C++ code):

 if(this->DesignMode || 
    LicenseManager::UsageMode == LicenseUsageMode::Designtime) 
    return;

This variable will always show the proper design boolean.

Answer 3

The solution of greggorob64 in C#:

if (DesignMode || LicenseManager.UsageMode == LicenseUsageMode.Designtime) 
{
    return;
}