<TelerikWindow Left="@TheLeft" Top="@TheTop" Draggable="true"
               LeftChanged="@LeftChangedHandler" TopChanged="@TopChangedHandler"
               Visible="true" Width="400px" Height="300px">
    <WindowTitle>Drag me!</WindowTitle>
    <WindowContent>When using Left and Top, make sure to update them in the view-model.</WindowContent>
    <WindowActions>
        <WindowAction Name="Minimize"></WindowAction>
        <WindowAction Name="Maximize"></WindowAction>
    </WindowActions>
</TelerikWindow>

@code{
    string TheLeft { get; set; } = "50px";
    string TheTop { get; set; } = "50px";

    async Task LeftChangedHandler(string currLeft)
    {
        float leftValue = float.Parse(currLeft.Replace("px", ""));
        Console.WriteLine("left " + leftValue);
        //left boundary
        if (leftValue < 0)
        {
            currLeft = "0px";
        }
        //right boundary - replace hardcoded values with current values from the viewport size
        //and take into account the dimensions of your window. This sample hardcodes values for brevity and clarity
        //you may find useful packages like this to get the viewport size https://www.nuget.org/packages/BlazorPro.BlazorSize/
        if (leftValue > 1000)
        {
            currLeft = "1000px";
        }


        TheLeft = currLeft;

        await DelayedRender();
    }

    async Task TopChangedHandler(string currTop)
    {
        float topValue = float.Parse(currTop.Replace("px", ""));
        Console.WriteLine("top: " + topValue);

        //top boundary
        if (topValue < 0)
        {
            currTop = "0px";
        }
        //bottom boundary - replace hardcoded values with current values from the viewport size
        //and take into account the dimensions of your window
        if (topValue > 600)
        {
            currTop = "600px";
        }

        TheTop = currTop;

        await DelayedRender();
    }

    async Task DelayedRender()
    {
        await Task.Run(async () =>
        {
            await Task.Delay(30);
            await InvokeAsync(StateHasChanged);
        });
    }
}

<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>