How to Check If Wpf Is Currently Executing in Design Mode or Not

Is there a way to check if WPF is currently executing in design mode or not?

I believe you are looking for GetIsInDesignMode, which takes a DependencyObject.

Ie.

// 'this' is your UI element
DesignerProperties.GetIsInDesignMode(this);

Edit: When using Silverlight / WP7, you should use IsInDesignTool since GetIsInDesignMode can sometimes return false while in Visual Studio:

DesignerProperties.IsInDesignTool

Edit: And finally, in the interest of completeness, the equivalent in WinRT / Metro / Windows Store applications is DesignModeEnabled:

Windows.ApplicationModel.DesignMode.DesignModeEnabled

How to check if i'm in run-time or design time?

DesignerProperties.GetIsInDesignMode(this); This would return true if you are in design-time.

How to know whether a control is at design-time or not?

Check if DesignMode is true or false. It's a property that belongs to the control base class.

How to tell if .NET code is being run by Visual Studio designer

To find out if you're in "design mode":

Windows Forms components (and controls) have a DesignMode property.
Windows Presentation Foundation controls should use the IsInDesignMode attached property.

Is there a DesignMode property in WPF?

Indeed there is:

System.ComponentModel.DesignerProperties.GetIsInDesignMode

Example:

using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;

public class MyUserControl : UserControl
{
    public MyUserControl()
    {
        if (DesignerProperties.GetIsInDesignMode(this))
        {
            // Design-mode specific functionality
        }
    }
}

Detecting design mode from a Control's constructor

You can use the LicenceUsageMode enumeration in the System.ComponentModel namespace:

bool designMode = (LicenseManager.UsageMode == LicenseUsageMode.Designtime);

How do I stop my ViewModel code from running in the designer?

DependencyObject dep = new DependencyObject();
if (DesignerProperties.GetIsInDesignMode(dep))
{
    ...
}