There should be a mean to restrict the possible values a user can input.

One should be able to show a desired time range i.e. from 8 am to 6 pm

Steps to reproduce:

1. Add a RadPropertyGrid to a form.
2. Select an object with DateTime property
3. Subscribe to the EditorInitialize event and set min and max date.
4. Run the application and open the property for edit. Type in a value outside the valid range and end edit. You will see that the invalid value is saved.

Keyboard input does not work in RadDateTimePicker when the Culture is ar-SA

Users should be able to increment the whole value of the RadMaskedEditBox using the Up/Down arrow keys or Mouse Wheel

Allow the RadDateTimePicker editor of RadGridView to allow replacement of the months' popup.

Resolution:   This behavior can be achieved when set the HeaderNavigationMode property to Zoom of RadCalendar. The feature is introduced in Q2 2014.  
For example: 
void radGridView1_CellEditorInitialized(object sender, Telerik.WinControls.UI.GridViewCellEventArgs e)
        {
            RadDateTimeEditor dtEditor = e.ActiveEditor as RadDateTimeEditor;
            if (dtEditor != null)
            {
                RadDateTimeEditorElement element = (RadDateTimeEditorElement)dtEditor.EditorElement;
                element.Calendar.HeaderNavigationMode = HeaderNavigationMode.Zoom;
            }
        }

ADD. Popup control which can host controls and be associated with a button or opened on request.

To reproduce - create a form with a button and on click open another form with couple of RadColorBoxes in it. After closing the child form the memory is not released.

Steps to reproduce:

radDateTimePicker1.Value = DateTime.Today; 
radDateTimePicker1.SetToNullValue(); 
radDateTimePicker1.Value = DateTime.Today;

RadTimePicker - unable to localize Close button Text using Localization Provider

Visual Style Builder is unable to start on computer with Italian regional settings.

Selection in RadDateTimePicker when the culture is ar-SA is not correct. Further, changing the selected date using the arrow keys does not set the right value.

Exception is thrown on key press if RadMaskedEditBox has MaskType set to Numeric, Mask to C2, and Value to Null.

RadDateTimePicker ValueChanging event cannot be canceled with e.Cancel = true;

FIX. RadSpinEditor - user should not be able to change the value of the control with the arrow keys when in ReadOnly mode

When you inherit from RadTextBox and override the OnKeyPress or OnKeyDown, those events are not fired.

FIX. RadMaskedEditBox - the minus sign is stripped our with ExcludePromptAndLiterals and IncludePrompt formats with currency mask, while it should not.

Improve the RadSpellChecker component by adding localization support.

1. Provide the 'Ignore' button above the 'Ignore All' button 

2. If no text is entered in the 'Change To' text field and the 'Change' button is clicked, the highlighted suggestion should be used instead.

3. After the 'Change' button is clicked, the 'Change To' text box should be cleared so that users don't have to delete the text string before entering something else.

Allow RadSpellChecker to perform check spelling for many controls.

Reason for denial: 
The RadSpellCheker knows the associated document and for example if a user presses ignore all (in as you type) this should be ignored only for specific documents. 
Also spell checker is inherited from MS component named 'Native Windows' which allows spell checker to receive a WND messages from the associated control.