Hello,

I've found a new bug regarding per-monitor DPI awareness in the latest WPF controls build (2020.1.115).

Applications start fine on the modern Windows 10 systems (1607 or later) but crash on previous Windows versions.

The conditions to reproduce:

• The application is launched on Windows version older than Windows 10 1607/Windows Server 2016. I've reproduced it on Windows 8.1/Windows Server 2012 R2, but I suppose it also affects Windows 10 1507/1511, and probably Windows 8/Windows Server 2012.
• Application manifest contains:

<dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true/PM</dpiAware>

Here is the stack trace:

System.EntryPointNotFoundException: Unable to find an entry point named 'GetDpiForSystem' in DLL 'User32.dll'.

   at Telerik.Windows.Controls.InternalWindow.Standard.NativeMethods.GetDpiForSystem()

   at Telerik.Windows.Controls.InternalWindow.Standard.DpiHelper.GetSystemScaleFactor()

   at Telerik.Windows.Controls.InternalWindow.Standard.DpiHelper.CalculateScaleFactor(IntPtr hwnd)

   at Telerik.Windows.Controls.InternalWindow.Standard.DpiHelper.GetPerMonitorDPIAwareScaleFactor(IntPtr hwnd)

   at Telerik.Windows.Controls.InternalWindow.ChromelessWindowHelper.<Initialize>b__81_0(Object sender, EventArgs args)

   at System.Windows.Window.OnSourceInitialized(EventArgs e)

   at System.Windows.Window.CreateSourceWindow(Boolean duringShow)

   at System.Windows.Window.CreateSourceWindowDuringShow()

   at System.Windows.Window.SafeCreateWindowDuringShow()

   at System.Windows.Window.ShowHelper(Object booleanBox)

   at System.Windows.Window.Show()

   at Telerik.Windows.Controls.InternalWindow.WindowWithNoChromeWindowHost.Open(Boolean isModal)

   at Telerik.Windows.Controls.WindowBase.ShowWindow(Boolean isModal)

   at Telerik.Windows.Controls.RadWindow.Show()

   at TelerikWpfCrash.App.OnStartup(StartupEventArgs e) in C:\Users\fedarovich\source\repos\Test\TelerikWpfCrash\TelerikWpfCrash\App.xaml.cs:line 20

The issue happens because the code calls the WinAPI functions not available on these OS versions (for example, GetDpiForSystem, but maybe there are more). 

I've attached a small example to reproduce this issue. It is for .Net Core 3.1, but the same issue exists in .Net Framework too.

Hi,

   There is a bug in version 2019.3.1023.45 RadWindow when I minimum and restore window from task bar

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.

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.

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!

When EventBinding is used in XAML to bind commands to events of Window or RadRibbonWindow (as it inherits Window), InvalidOperationException is thrown in design-time.

Workarounds: 
1. Attach an event handler directly to the events of the Window (RadRibbonWindow)
2. (more MVVM-friendly) use Behavior to attach the appropriate event handler.