On Windwos XP , Windows Vista, Windows 7, Windows 11 the RadForm/ShapedForm hides the taskbar when it is set to Auto-Hide. When you try to show the taskbar it appears behind (under) the RadForm instead of infront (over) it.

1. Create a new Form that inherits from RadForm and add some rad controls.
2. Checkin the file in your source control system
3. Open the form in design time will cause checkout

Setting the RightToLeftLayout to true together with RightToLeft = Yes, cuts off the form

1. Create RadRibbonForm and add code to start maximized 
2. Add status strip with some items on the ribbon form 
3. in the form constructor create a MDI child form, set it to start maximized and show it 
4. The result is that there is gap between the child form and the status strip

Workaround:
protected override void OnShown(EventArgs e)
{
    base.OnShown(e);
 
    this.WindowState = FormWindowState.Minimized;
    this.WindowState = FormWindowState.Maximized;
}

Workaround: set the RadRibbonFormBehavior1.AllowTheming property of the form to false

public class RadForm1
{
	public RadForm1()
	{
		InitializeComponent();

		this.RadRibbonFormBehavior1.AllowTheming = false;

	}
}

The controls inside the form are not scaled correctly when the Form is shown on a monitor with DPI higher than 150%. An important step here is that the main monitor where the form is shown has a higher DPI. Moving the form from a monitor with 100% to a monitor with a higher DPI will not reproduce this behavior.

To reproduce:
RadForm form = new RadForm();
form.WindowState = FormWindowState.Maximized;
form.Text = string.Format("Child {0}", MdiChildren.Length + 1);
form.MdiParent = this;
form.Show();

Hover the Form's title bar the tooltip should start flashing/blinking

To reproduce:

public partial class RadRibbonForm1 : Telerik.WinControls.UI.RadRibbonForm
    {
        public RadRibbonForm1()
        {
            InitializeComponent();
            this.AllowAero = true;
            this.RibbonBar.QuickAccessToolbarBelowRibbon = false;
        }
    }

Note: the system buttons not always handle the mouse click.

Workaround: set AllowAero to false OR RibbonBar.QuickAccessToolbarBelowRibbon to true.

RadRibbonForm is flickering, when it is used as MDI Parent with applied background image.

To reproduce:
1. Drop a RadGridView and RadButton on Rad Form.
2. Set gris Anchor property to Top-Right-Bottom-Left and the buttons Anchor property to Right-Bottom.
3. Make sure that the RadForm's size is exactly as your desktop resolution(e.g. my 'RadForm' size and desktop resolution are 1920x1080).
4. Change its 'AutoScaleMode' property's value to 'Font'.
5. Build project.
6. Copy the resulted executable on your desktop and name it 'RadControlsWinFormsApp_Font'
7. Select again the RadForm.
8. Change its 'AutoScaleMode' property's value to 'DPI'
9. Build project.
10. Copy the resulted executable on your desktop and name it 'RadControlsWinFormsApp_DPI'
11. Select again the RadForm
12. Change its 'AutoScaleMode' property's value to 'Inherit'
13. Build project
14. Copy the resulted executable on your desktop and name it 'RadControlsWinFormsApp_Inherit'
15. Change your desktop resolution to a lower one (e.g. I've change it from 1920x1080 to 1600x900)
16. 'Auto-Hide' the Window's taskbar
17. Run the executables and see the results:
   17.1 In case of 'RadControlsWinFormsApp_Font' application, you should see that the 'RadGridView' control gets truncated + the lower right 'RadButton' is not visible anymore
   17.2 In case of 'RadControlsWinFormsApp_DPI' application, you should see that the 'RadGridView' control gets truncated + the lower right 'RadButton' is not visible anymore
   17.3 In case of 'RadControlsWinFormsApp_Inherit' application, you should see the controls on the form as you initially placed them.

Also this issue appears on 'Windows XP SP3 x86' and also on 'Windows 7 SP1 x64' .

Workaround:
- Set AutoScaleMode property to None or Inherit.

The attached video shows how you can reproduce this.

The issue is easily reproducible on a remote Windows 7 machine.

RadForm has AllowTheming property which enables/disables the aero effects of RadForm and when you set it to false our theming mechanism is disabled. Add a property,e.g. ThemeResolutionService.ApplicationAllowTheming, which will control the AllowTheming of all forms in the application. In addition, RadForm should have a new property,e.g. EnableApplicationAllowTheming, which will control whether the respective form should respect the global property or not.

Case 1: 
ThemeResolutionService.ApplicationAllowTheming = true
RadForm1.EnableApplicationAllowTheming=true //this property is set to true; this indicates that the local AllowTheming property WON'T be respected and the global property ApplicationAllowTheming  takes effect
RadForm1.AllowTheming=false

RadForm1 has theming.

RadForm2.EnableApplicationAllowTheming=false //this property is set to false; this indicates that the local AllowTheming WILL be respected and the global property ApplicationAllowTheming  DOESN'T take effect
RadForm2.AllowTheming=false

RadForm2 doesn't have theming.

Case 2:
ThemeResolutionService.ApplicationAllowTheming = false
RadForm1.EnableApplicationAllowTheming=true //this property is set to true; this indicates that the local AllowTheming property WON'T be respected and the global property ApplicationAllowTheming  takes effect
RadForm1.AllowTheming=true

RadForm1 doesn't have theming.

RadForm2.EnableApplicationAllowTheming=false //this property is set to false; this indicates that the local AllowTheming WILL be respected and the global property ApplicationAllowTheming  DOESN'T take effect
RadForm2.AllowTheming=true

RadForm2 has theming.

Note: the same logic is implemented for the ThemeResolutionService.ApplicationThemeName: http://docs.telerik.com/devtools/winforms/themes/using-a-default-theme-for-the-entire-application

The issue can be reproduced by creating a form with a width of 1200 pixels in an application that is DPI aware. Then the project is run on a tablet with low resolution and an increased DPI, e.g. 1024 x 768 and scaling 120%.

Workaround:
Public Class RadForm1
    Sub New()

        InitializeComponent()

        Dim g = Me.CreateGraphics()
        Dim scale = 96.0 / g.DpiX
        Me.Size = New Size(scale * Me.ClientSize.Width, scale * Me.ClientSize.Height)
        g.Dispose()
        Me.WindowState = FormWindowState.Normal
    End Sub
End Class

VS 2022, Telerik 2022.2.510, NET 6.0 (sample app is attached)

1. Creating sample Telerik WinForms App.
2. Add a RadTextBox
3. Load Event with code
radTextBox1.Text = this.Size.ToString();

4. Run the App
5. Close the App
6. Move the RadTextBox Control at design time.
In design, the height of the form is 2 pixels taller.
Run these steps in a loop. After a few hours of work, the form exceeds the size of the screen.

To reproduce:
-Set RTL via the insane:
RadMessageBox.Instance.RightToLeft = RightToLeft.Yes;

- You will notice that layout is not changed when the messagebox is shown.

Worlaround:
- Use the RadMessageBox show method with the following parameters:

RadMessageBox.Show(this, "test", "caption", MessageBoxButtons.OKCancel, icon, MessageBoxDefaultButton.Button1, RightToLeft.Yes);

Create a custom theme starting from Aqua theme. Change the Font for RadLabelElement-TextPrimitive to "Microsoft Sans Serif, 10pt". Save the theme and apply it to the entire application. Show several times a RadMessageBox with long text. The first time the RadMessageBox is sized correcly to its content. Each next showing, cuts off the text.

Workaround:  the possible workaround that I can suggest is to dispose the RadMessageBox instance after showing it:

Private Sub RadButton1_Click(sender As Object, e As EventArgs) Handles RadButton1.Click
    RadMessageBox.Show(Me, "If you have some veeeeery long sample text, the messagebox " & _
                       "should be resized according to its content.", "Caption", MessageBoxButtons.OK, My.Resources.image)
    RadMessageBox.Instance.Dispose()
End Sub

When the form border style is set to none the form still has minimum width.

To reproduce:

public Form1()
{
    InitializeComponent();

    RadMessageBox.Instance.AutoSize = true;
}

private void radButton1_Click(object sender, EventArgs e)
{
    string msg = string.Format("Test", (sender as RadButton).Name);
    RadMessageBox.Show(msg, "Error");
}

Note that the size of  RadMessageBox is adjusted automatically to display the whole content. Hence, it is not necessary to set the RadMessageBox.Instance.AutoSize property to true.