verified still present in 2026.2.519 — RadCalendarScript.js

When `EnableNavigationAnimation` is enabled (the default) and the browser zoom is not 100% (and Windows uses fractional display scaling such as 125%/150%),
navigating the RadCalendar to the NEXT month removes the day grid and never renders the new one. The calendar title updates, but the view area stays empty permanently. 
Because `_enableNavigation(false)` and `EnableDateSelect = false` are set before the animation and only restored when it completes, the calendar is also left with navigation 
and date selection disabled — the control is dead until the page is reloaded.

Navigating BACKWARD works correctly (see root cause below for why), which is a useful way to confirm this specific bug.

End users hit this routinely because Chrome persists per-site zoom and many laptops default to 125%/150% display scaling.

 Steps to reproduce:
 1. Page with a default RadCalendar:

<telerik:RadCalendar ID="RadCalendar1" runat="server" EnableNavigationAnimation="true" />

  2. Open in Chrome, set zoom to 110% (Ctrl and +), reload.
  3. Click the "next month" arrow (repeat at a couple of zoom levels, e.g. 110%,
     125%, 150% — whether a given level triggers it depends on rounding of the
     calendar's rendered width).

c = function () {
          o > 0 && r.scrollLeft + r.offsetWidth < r.scrollWidth ||
          o < 0 && r.scrollLeft > 0
              ? (r.scrollLeft += 10 * o, window.setTimeout(c, 10))
              : d();   // d() re-attaches the new table and re-enables the control
      };

`Element.scrollLeft` is a fractional double, while `offsetWidth`/`scrollWidth` are rounded integers. At zoom levels other than 100%, `scrollLeft` clamps at a fractional maximum (e.g. 219.4545) while the rounded widths suggest an integer maximum (e.g. 220 with scrollWidth 440). The forward-direction termination
 check `scrollLeft + offsetWidth < scrollWidth` (439.45 < 440) then remains true forever: `scrollLeft += 10` is clamped and makes no further progress, so the loop reschedules itself indefinitely and `d()` is never called. The new view table is never appended, and navigation/date selection are never re-enabled.

The backward direction terminates on `scrollLeft > 0`, and `scrollLeft` clamps to exactly 0 — which is why only forward navigation is affected.

There is no property indicating the next DateTime that user is going to,

for example, we are in November/2022 and the end user click on "<" back button,

the event return the current date.

RadCalendar1_OnHeaderCellRender

the  var nMes = cal.FocusedDate.Month; to return the current month.

When MultiViewColumns > 2 the the month views of the Calendar are not aligned properly. The problem occurs if the week count in the months is different and the ShowOtherMonthsDays property is set to false.

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.

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";

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.

We have just got issue with WCAG compatibility when applying for WCAG certification.
 The problem is that RadCalendar used for RadDatePicker has a strange behaviour when tabbing. We can't get focus to buttons (<<,<, >, >>)  that are in the header of the Calendar popup. We can successively navigate contemt of the Callendar -days of the month both with Tab and arrow keys (with EnableKeyboardNavigation="true"
 ) , but not to header buttons.
 We found nearly the same problem on Telerik demo: http://demos.telerik.com/aspnet-ajax/calendar/examples/functionality/keyboardnavigation/defaultcs.aspx

 Please look that Calendar at the top of the page does not allow select its header buttons. But the one in popup inside RadDatePicker can tab to its header buttons. 
 (however in strange way order is: days navigation inside Calendar1 by arrows, Tab- RadCalendar1, Tab- header of Callendar1 first button: <<)