The default WPF PrintDialog cannot print asynchronously when it is shown in UI. However, you may see the demo in this forum post showing how to create custom PrintDialog and perform async printing with it:
http://www.telerik.com/forums/pdfviewer-print-makes-ui-unresponsive#js0YdzFWc0Oa8C3g6a18lg

Currently PropertyDefinitions have only one Property for DataBinding, which is very strange solution.

All these instances are DependencyObject, but at the same time they are not in the visual tree and we could not bind to a visibility or to readonly or to any other property without some starnge sorkarounds (why this was designed in this way?).

This makes these objects almost useless. becuae we cannot fully use them in an MVVM way (bindings, multiibindings, etc.)

Possible solutions:

1. provide bindings for all properties to make them be bindable withput any workarounds
2. Change PropertyDefinitions to something that will live inside visual tree.

Please add an option to modify the corner radius for TrackBackground and UncheckedTrackBackground in the RadToggleSwitchButton template.

The radius of both rectangles is hard-coded to 9 (TrackBackground)  / 12 (UncheckedTrackbackground) (Why are they different btw?). While it is possible to set the TrackHeight and TrackWidth to custom values, this doesn't really work well for the Fluent theme right now due to the radii quickly becoming disproportionally large or small compared to the TrackHeight. This results in the control losing its shape and becoming more and more egg-shaped or rectangular, depending on whether you decrease or increase the TrackHeight.

Ideally, the Radii would be automatically computed, depending on the selected TrackHeight (Floor(TrackHeight/2) ?), however, a manual solution would also be a lot better than nothing. That way we could at lease define proportionally matching values via styles.

Currently, when you cancel the Filtering event the field filter (displayed when FilteringMode="FilterRow") will clear any entered text and the funnel icon won't change its color (like when the filter is active). Add an option in the Filtering event, similar to the Sorting event which allows you to manually set the sorting state of the column which will affect the UI (showing and changing the sort indicator icon).

In the case with the Filtering event, there should be an option if the funnel icon should be highlighted. In other words the setting should allow you to manually say if the filter is active or not. Also, the input text in the field filter should be preserved and possible an option to change this value may be added in the event arguments. This will allow you to implement custom filtering and keep the UI state of the field filter.

Currently the MouseWheel event used to zoom is not handled which means that the event will bubble to the parent elements which can lead to scrolling issues. Add an option to handle the MouseWheel event when the chart zooming is enabled.

To get the desired result, you can handle the MouseWheel event of the chart manually.

 private void RadCartesianChart_MouseWheel(object sender, MouseWheelEventArgs e)
 {
     e.Handled = true;
 }