property Chart.AllowZoomOnFly as ZoomOnFlyEnum
Magnifies the bar from the cursor, when the user presses the CTRL / SHIFT key combination.

ZoomOnFlyEnum A ZoomOnFlyEnum expression, or combination of the giving flags, that specifies the way the Zoom-OnFly view is displayed. For instance, if the AllowZoomOnFly is exZoomOnFly, the Zoom-OnFly view is show once the user presses the SHIFT + CTRL keys combination on the chart.
By default, the AllowZoomOnFly property is 0, exNoZoomOnFly. In other words, the Zoom-OnFly view is never displayed by default. The Zoom-OnFly view was provided to let you magnify a portion of the chart without affecting the chart's scale. The Zoom-OnFly view displays the item and its neighbors from the cursor, and additional information about the bar from the cursor. The Zoom-OnFly scale is indicating by the chart's ResizeUnitScale property. If the chart's ResizeUnitScale property is not specified, the Zoom-OnFly uses the chart's UnitScale property to indicate the inside scale. The ZoomOnFlyCaption property indicates the HTML caption to be displayed as addition information for the bar/task from the cursor. The BackColorZoomOnFly property indicates the Zoom-OnFly's background color. The Zoom-OnFly view is shown on the chart once the user presses the CTRL +/ SHIFT keys and the the chart is active/focused. The Label property indicates the label to be shown in the Zoom-OnFly view. Set the ZoomOnFlyCaption property on empty, to display no addition information about the bar from the cursor. Use the SelectOnClick property to prevent selecting a row / item when clicking the chart portion of the control.

The following screen shot shows the Zoom-OnFly view, after the user presses the CTRL + SHIFT keys combination ( You can notice that the inside scale displays hours, while the master chart displays days ):

The following screen shot shows the chart before pressing the CTRL + SHIFT keys ( before showing the Zoom-OnFly view ):

This feature could be very useful:

Click here to watch a movie on how you can resize or move bars if precision is required.

Here's a few samples on how to use the AllowZoomOnFly property: