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".

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

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

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);
})

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";

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;
}

Test Environment:

OS: Windows_11

When the FastNavigationPrevImage and NavigationPrevImage properties are set the font-icon based buttons are replaced with image buttons. However, the Prev and FastPrev-related images are missing the required float: left CSS setting and are rendered in the center of the calendar title bar.