I have a page with a Gantt chart and a Button. The button navigates to another page in the app (NavigationManager.NavigateTo()). When I click the button an exception is thrown:

Exception trace: Error: Microsoft.JSInterop.JSException: An exception occurred executing JS interop: The JSON value could not be converted to System.Double. Path: $ | LineNumber: 0 | BytePositionInLine: 4.. See InnerException for more details. ---> System.Text.Json.JsonException: The JSON value could not be converted to System.Double. Path: $ | LineNumber: 0 | BytePositionInLine: 4.
 ---> System.InvalidOperationException: Cannot get the value of a token type 'Null' as a number.

The Planned vs Actual functionality of the Gantt allows you to compare actual start and end dates to originally planned dates.

In Telerik UI for AJAX, you can see the Actual vs Planned feature at work. 

1. Go to https://demos.telerik.com/blazor-ui/gantt/templates

2. Scroll to the end of the timeline horizontally

3. Move the mouse pointer to timelineTooltip appears in the wrong place

The Tooltip Template of the Gantt behaves strangely in a WASM application. It flickers and does not display any information. Reproduction in REPL which is essentially a WASM app: https://blazorrepl.telerik.com/QQFEapOg56MCIhIK48.

The issue is not reproducible in a server-side application using the same code.

How to get only the year and date in the Gantt Chart Tooltip template? The DataAttribute is not a valid date string.

<TooltipTemplate>
     <h4>@(((TooltipTemplateContext)context).Title)</h4>
     <h5>Start: @(((TooltipTemplateContext)context).DataAttributes["start"])</h5>
     <h5>End: @(((TooltipTemplateContext)context).DataAttributes["end"])</h5>

</TooltipTemplate>

Please allow the Gantt TimeLine to be read-only and prohibit task editing, resizing, dragging and dependency changes.

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Possible workaround: Read-only Gantt TimeLine (forum thread)

Hello, It should be possible to rearrange the order of the Gantt elements using drag and drop. This function already exists in the TreeList component and is also necessary for us in gantt.

Zooming levels would be great

GanttCommandButton Command="ZoomIn|ZoomOut|ZoomToFit"...>

The current Views (Day/Week/Month/Year) are nice, but custom zooming is needed sometimes.

There should be a way to programatically scroll to a specific day in the timeline.

UseCase 1: Goto Today Button

UseCase 2: Upon clicking on a line in tree list the timeline should display this task in the timeline.

Since there is no "goto today" functionality (which I requested in a separate ticket). It is a pain to find the current timeslot in the timeline by scrolling.

The current timeslot should be highlighted by a specific background color or by a vertical line through the timeline.