This exception is thrown when the CanExecute method of the Command bound to a response button returns false when the response button key is pressed. 

The Window doesn't resize correctly when dragged from the primary monitor (with taskbar) and docked to the top of the screen of a secondary monitor (no taskbar) in order to maximize it and "Show window contents while dragging" Windows system setting is disabled.

When creating themed applications using RadControls, the standard Windows MessageBox control looks out of place.  With that in mind, the predefined RadWindows (Alert and Confirm) seem to be natural replacements for a typical MessageBox.  

However, when these dialogs open, they are silent  That is, they don't play any error, warning, or question sounds like the standard MessageBox - which makes them seem "strange" when used as a replacement.

Adding sounds to (for instance) the Alert window is fairly simple and can be accomplished like this:

RadWindow.Alert(new DialogParameters()
{
    Content = new System.Windows.Controls.TextBlock {
        Text = ex.Message, Width = 250, TextWrapping = TextWrapping.Wrap },
    Header = "Update Error",
    Opened = (alertDialog, eventArgs) => System.Media.SystemSounds.Exclamation.Play()
});

Though, it'd be nice if the ability to play a sound was built-in.  I'd suggest that the DialogParameters class used to customize the predefined dialogs be extended to support a SystemSound member of type System.Media.SystemSounds which, if defined, would play the specified sound when the dialog opens.

When the RadWindow is initialized on a monitor and then another monitor with higher resolution is added during runtime, moving the RadWindow to the monitor with higher resolution, causes the RadWindows' width and height to be limited to the ones of the initial monitor.

After fixing this BUG (Release LIB 2019.3.930), an additional issue is found.

A window is in Maximized or Normal state, click on the application icon in the taskbar to minimize it and click again to restore the window. It gets clipped to ~160*26 pixels. After clicking on this header, it gets restored to Maximized or Normal state depending on the initial state.

I have a two-monitor setup with identical resolutions (FullHD on both monitors) and Scale is 100% on both monitors.

Initial BUG was fixed in recent update.

One issue still exists:

When minimizing a window that is maximized in the way the intial issue described the problem, and you reactivate it by clicking on its "TaskBarIcon", the window gets clipped incorrectly again.

If you try to show a window, and right afterwards call RadWindow.Alert() or any other prompt dialog, the main window automatically closes.

To work this around show the prompt in the Loaded event handler of the RadWindow.

This is reproducible when you disable the automation peers by setting the AutomationManager.AutomationMode static property to Disabled.

It happens when you open a new RadWindow dialog (using the ShowDialog method), and the close it. After this, when you interact with the main window (click a button, hover a GridView, etc.) the exception occurs.

The exception is thrown only in the Output pane of Visual Studio and it doesn't cause any harm to the application. You can safely ignore it.

The exception message is "Invalid window handle".

To work this around you can enable the "Enable Just My Code" option in Visual Studio.

Moving a window fast on low performance machine or between two monitors causes incorrect offset to be applied to the mouse cursor

The RadWindow's size shrinks while dragging it on a monitor with high DPI scale which causes it to shake a bit. In other words, the dragging is not smooth.

This was reproduced on a monitor with DPI scale set to 175%.
This is reproducible if you set the RadWindowInteropHelper.AllowTransparency on the RadWindow control (regardless of the value - True or False).
This is more noticeable in .NetCore projects.

This happens when RadWindowInteropHelper.AllowTransparency is set to False and RadWindow is implemented as UserControl. The Window need to be maximized firstly on the main screen and then on the secondary in order for issue to be reproduced.

The issue also affects the ToolWindow that RadDocking uses for its floating Pane. In order to reproduce the problem, the primary monitor needs to have its DPI higher than the secondary one.

The Window gets clipped on the right side when using a dual monitor setup when the taskbar is on the left/right side of the screen and the app must be running maximized on the secondary screen.

The header buttons elements are not on the proper places when the window is on a monitor with different DPI. To reproduce this the DPI of the monitors should be different for example 125% (main) and 150% (secondary). Also, to reproduce this you will need to enable the DPI awareness of the application by setting the dpiAware and dpiAwareness settings in the app.manifest file.

Environment: VS Community 2019 (16.0.3), with .NET Framework 4.8 (release version, run-time and developer pack installed), Windows 10 Pro October 2018

Telerik UI version: latest (2019.1.220.45)

 

When VS2019 opened, Telerik UI for WPF should have been found under the "Extension" menu --> Telerik --> Telerik UI for WPF. However, there is only "Telerik UI for WinForms" under "Telerik" now. There is neither "Telerik scenario" in the "Add New Item" window so no RadForms can be created. Manually replacing <Window> in XAML to <telerik:RadWindow> does change the appearance of the window in the designer, but the properties in the Property window does not change accordingly to RadForms but still WPF standard Form ones. Toolboxes shows current lists of Telerik UI for WPF controls and they can be correctly created (at least RadButton). "Repair" in the Progress Control Panel doesn't fix this problem.

 

Thanks!

RadWindow.Confirm default button is OK, in order to change that presently we have to extract and modify styles, set FocusManager.FocusedElement binding to Cancel and set the ContentStyle property in code. 
It would be much more user friendly if this could be controlled by a simple property.

 

This behavior is presented with the ShowDialog() method of the WPF native Window control. Basically, the ShowDialog() method could return a value (true, false, null). Currently, the method is "void".

Scheduled for:
The fix for this issue will be available with LIB (version 2018.3.1224) scheduled for publishing on Monday, 24th December 2018.