RadCalendar and RadDatePicker cannot pass the following check by https://achecker.ca/checker/index.php

WCAG 2.0 guideline
Section

1.3 Adaptable: Create content that can be presented in different ways (for example simpler layout) without losing information or structure.
Success Criteria 1.3.1 Info and Relationships (A) 

Check 245: Data table with more than one row/column of headers does not use id and headers attributes to identify cells.

Repair: Add id and headers attributes to table cells so they identify the cells that relate to the headers.

Error Line 597, Column 8:
<table id="ctl00_ContentPlaceholder1_RadDatePicker1_calendar_Top" class="rcMainTable" summary="Table …

Steps to reproduce

Go to https://achecker.ca/checker/index.php

Paste https://demos.telerik.com/aspnet-ajax/datepicker/accessibilityandinternationalization/wcag2.0andsection508accessibility/defaultcs.aspx
or 
https://demos.telerik.com/aspnet-ajax/calendar/accessibility-and-internationalization/wcag-2.0-and-section-508-accessibility/defaultcs.aspx

See the results -> 

Check 245: Data table with more than one row/column of headers does not use id and headers attributes to identify cells.
Repair: Add id and headers attributes to table cells so they identify the cells that relate to the headers.
Error Line 568, Column 8:
<table id="ctl00_ContentPlaceholder1_RadDatePicker1_calendar_Top" class="rcMainTable" summary="Table ...


=======================================

WORKAROUND:

$telerik.$("table.rcMainTable tbody th").each(function (idx, el) {
    var thId = $telerik.$(el).attr("id");
    $telerik.$(el).siblings("td").attr("header", thId);
})

Open a demo page https://demos.telerik.com/aspnet-ajax/datetimepicker/overview/defaultcs.aspx?skin=Bootstrap and select Bootstrap skin. You will see that the right corners of the clock button are cutted down.

Workaround:
.RadPicker .rcSelect {
    border-top-right-radius: 4px !important;
    border-bottom-right-radius: 4px !important;
}

Workaround 1) Use .resx files as the attached ones 

Workaround 2) Set properties to ViewState
        RadMonthYearPicker1.MonthYearNavigationSettings.ViewState["_mCancelButtonCaption"] = "my cancel";
        RadMonthYearPicker1.MonthYearNavigationSettings.ViewState["_mTodayButtonCaption"] = "my today";
        RadMonthYearPicker1.MonthYearNavigationSettings.ViewState["_mOkButtonCaption"] = "my ok";

-> When DatePicker renders for the first time, it applies the CSS according to the selected skin.
Reference Image: Comtrol in Filter Panel first time render.jpg

-> But as soon as I enter into an edit mode or insert than the CSS is not applied to the control and the design of the RadCalender is breaking somehow.
Reference Image: Control while Editing.jpg

-> Also entering into edit or insert break the design of the other RadCalender control placed in filter panel.
Reference Image: Control in Filter Panel.jpg

As I'm using RadDatePicker in my Grid,

In RadGrid for the first time, the image beside the calendar control renders as expected.

As soon as I enter into "InLine" edit mode there would be 2 images rendered beside the control.

And after clicking on cancel there is no change in the image beside the control.

Also attached the screenshot for the same.

When the culture is set using Thread.CurrentThread.CurrentUICulture = new CultureInfo("it");
The following exception is thrown
https://www.screencast.com/t/YnQstdBUrY

Hi,

I would like RadDatePicker to have DropDown Combo boxes for years and months like attached picture please.

Kind Regards,
Asaf

This suggestion is add a css class to each anchor tag for each day, a unique css, like:
class='day20180213'.
with this we can make a css definition:
holydays.css
       day20180213 { background-color:red } // carnival
/* day YYYYmmDD */

this option has unlimited uses for any reason you want.

how it will works:
<td title="terça-feira, fevereiro 13, 2018" class="rcSelected" style=""><a class='day20180213' href="#">13</a></td>

If it is possible, I'd like to be able to select the hour and minute individually from the same popup/dropdown.   
Currently, if you set the interval to anything less than 15 mins the list becomes far too big, imo, and forcing the list to scroll isn't always the most usable way to do things, especially if that list is particularly large (intervals of 5 mins or lower).

It would be really handy if the user could somehow choose the hour and minute separately before the popup/dropdown closes. This would minimise space used because you wouldn't need every instance of each hour/minute combination. You'd just need the hours displayed, and the minutes displayed.

The RadCalendar AccessKey property does not move focus to the RadCalendar control.
For example, set the AccessKey="K" for the RadCalendar.  

<telerik:RadCalendar ID="RadCalendar1" RenderMode="Lightweight" AutoPostBack="true" AccessKey="K"
         EnableKeyboardNavigation="true" EnableAriaSupport="true" EnableMultiSelect="true" runat="server"></telerik:RadCalendar>

However, focused is not moved to the Calendar with the AccessKey using ALT + Shift + key or ALT + key depending on the web browser. Please implement AccessKey for RadCalendar.

Thank You,
Carla

RadMonthYearPicker is missing form the SkinManager's ControlTypeToApplyskin collection

RadDatePicker/RadDateTimePicker can not set different date than the current one in Win10 (IE11 and Edge) when Finnish and Norwegian culture is used.

Microsoft changed the Time separator for these cultures, it breaks not only our JavaScript parsing but the .NET parsing as well.
https://connect.microsoft.com/VisualStudio/Feedback/Details/1621722

The issue is fixed for Q3 2015 SP1. Internally we change the TimeSeparator used by the DateInput to ":" for cultures where it is the same as the DateSeparator. It will not affect the DateFormatString.

Put more than two RadDatePicker with single SharedCalendar on page. some RadDatePicker are in side of UpdatePanel with a button in it. when I press that button RadDatePicker behaviour is strange. 
RadDatePicker inside UpdatePanel not opening Calendar popup while RadDatePicker outside UpdatePanel opens calendar popup but gives javascript error on any date selection. the javascript error is "Unable to get property '_selectedDates' of undefined or null reference".
It looks like it is destroying shared calendar object on partial postback.
Please find below sample code to replicate the issue. after clicking "Submit" button, it doesn't open calendar popup for "Date 2" and for "Date 1" it opens but doesn't allow to select date and gives JavaScript error.

----------------------
<asp:ScriptManager ID="sc1" runat="server" />
<telerik:RadCalendar ID="dtCal" runat="server" EnableMultiSelect="false" />
Date 1:
<telerik:RadDatePicker ID="dt1" Width="103px" runat="server" SharedCalendarID="dtCal" />
<hr />
<asp:UpdatePanel runat="server" ID="up">
	<ContentTemplate>
		Date 2:
		<telerik:RadDatePicker ID="dt2" Width="103px" runat="server" SharedCalendarID="dtCal" />
		<br />
		<asp:Button runat="server" ID="btnDT" Text="Submit" />
	</ContentTemplate>
</asp:UpdatePanel>
----------------------

When i add all controls in UpdatePanel it works properly. but Actual code is much more complex than above sample with too many lines of javascript code and many date pickers on single page and simply all Calendar and DatePicker controls can not be moved in UpdatePanel.

When handling the SelectionChanged event on a Calendar with EnableMultiSelect="true", there is no way to determine the new selected date(s). The SelectedDatesEventArgs exposes the entire range of selected dates, but it does not tell which of those dates were previously selected. Add a property to the event args that would expose this.

OR

Add an attribute to the RadCalendar when EnableMultiSelect="true" to "DeselectWhenSelectingNewDates." If this is set to true, any date selection on the calendar would deselect any previously selected dates.

When using min/max date the invalid dates have almost identical styling as the valid ones, this makes it hard for the user to see what dates are valid.

It would be nice of there was some way of telling them apart except by hovering over them.

Also when using "metro theme" the invalid date overrides the styling for dates belonging to "other month".

while typing the time in the kendo timepicker there should display the suggestion same like as available in the silverlight. If there is any feature please let us know.
Kindly refer enclosed snapshot of silverlight application.