<TelerikContextMenu Data="@MenuItems" Selector="#menu-target"
                    Class="menu-on-top" />

<style>
    .menu-on-top,
    .k-animation-container:has(.menu-on-top) {
        z-index: 11000 !important;
    }
</style>

<TelerikWindow Width="240px" Height="160px"
               Top="100px" Left="100px"
               Visible="true" Modal="true">
    <WindowTitle>Window</WindowTitle>
    <WindowContent>
        <div style="height:60px;border: 1px solid;"
             id="menu-target">Right-click me</div>
    </WindowContent>
</TelerikWindow>

@code {
    List<ContextMenuItem> MenuItems { get; set; } = new List<ContextMenuItem>();

    protected override void OnInitialized()
    {
        for (int i = 1; i <= 7; i++)
        {
            MenuItems.Add(new ContextMenuItem() { Text = $"Menu item {i}" });
        }

        base.OnInitialized();
    }

    public class ContextMenuItem
    {
        public string Text { get; set; } = string.Empty;
    }
}

<TelerikWindow Width="80%"
                Height="auto"
                Top="404px"
                State="WindowState.Minimized"
                Left="200px"                        
                Class="myClass"
                Visible="true"
><WindowTitle>My Title</WindowTitle><WindowActions><WindowAction Name="Minimize"></WindowAction></WindowActions><WindowContent><h1>My Content</h1></WindowContent></TelerikWindow>
 
Window starts out minimized, with proper width, height, top and left.
Clicking maximize button clears the top and left property, and resets position every time you open/close.
Click/dragging to move the window will reapply top/left property, and then maximize/minimize works properly.
 
If you change the state to to WindowState.Maximized, it has the correct top/left property, but resets the width/height properties.
Window is not draggable.
 
Not setting the State at all is the only way to have proper behavior.
    
    
        
    
    
        
    

<TelerikWindow Visible="true" Class="workaround-for-touch-drag">
    <WindowTitle>the title</WindowTitle>
    <WindowContent>the content</WindowContent>
</TelerikWindow>

<style>
    .workaround-for-touch-drag {
        touch-action: none;
    }
</style>

<div style="height:400px;"></div>
<TelerikButton Icon="window" OnClick=@(()=> WindowVisible = true)>Open Modal</TelerikButton>
<div style="height:400px;"></div>

<TelerikWindow Class="demo-window" Width="500px" Height="300px" Centered="true" @bind-Visible=@WindowVisible Modal="true">
    <WindowTitle>
        <strong>Modal Window</strong>
    </WindowTitle>
    <WindowActions>
        <WindowAction Name="Close" />
    </WindowActions>
    <WindowContent>
        <p>Click the close button to dismiss this modal dialog.</p>
    </WindowContent>
</TelerikWindow>

@code { public bool WindowVisible { get; set; } }

<style type="text/css">
    .demo-window {
        z-index: 44444;
    }
</style>

<TelerikWindow Class="@( isMinimized ? "minimize-window" : "maximize-window" )"
               Width="500px"
               Height="@Height"
               Top="40%"
               Left="45%"
               Visible="true">
    <WindowTitle>
        <strong>Status</strong>
    </WindowTitle>
    <WindowActions>
        <WindowAction Name="MyCustomMinimize" OnClick="@CustomMinimize" Icon="@IconName.WindowMinimize"></WindowAction>
        @if (isMinimized)
        {
            <WindowAction Name="MyCustomMaximize" OnClick="@CustomMaximize" Icon="@IconName.Window"></WindowAction>
        }
        <WindowAction Name="Close"></WindowAction>
    </WindowActions>
    <WindowContent>
        <form class="k-form">
            <fieldset class="k-form-fieldset">
                <legend class="k-form-legend">User Details</legend>

                <label class="k-form-field">
                    <span>First Name</span>
                    <input class="k-textbox" placeholder="Your Name" />
                </label>
                <label class="k-form-field">
                    <span>Last Name</span>
                    <input class="k-textbox" placeholder="Your Last Name" />
                </label>
            </fieldset>
        </form>
    </WindowContent>
</TelerikWindow>

@code {
    public bool isMinimized { get; set; }

    public string Height { get; set; } = "350px";

    private void CustomMinimize()
    {
        isMinimized = true;
        Height = "auto";
    }

    private void CustomMaximize()
    {
        isMinimized = false;
        Height = "350px";
    }

}

<style>
    .minimize-window .k-content {
        display: none;
        padding: 0px !important;
    }

    .maximize-window .k-content {
        display: block;
        padding: 16px 16px;
    }
</style>