Office Addin - First Letter Navigation in menus

Some UI components, such as dropdow lists, do support first letter navigation, i.e. lets the user navigate through the items of a list based on the first letter of the item's title. Here is a concreate example:
In Word, go to File > Options > General > Office Background > Down arrow (to open the dropdown list). In here, if I press 'C' once, I land on 'Calligraphy'. If I press 'S' once, I land on 'School Supplies', press 'S' a second time I land on 'Spring', press 'S' a third time I land on 'Starts', and so forth.

However, such navigation mechanism is not supported for menu components. For example:
In Word, go to Insert > Link > Recent items. I have a long list of recently accessed Word of Excel documents (let's call them Document_1, Document_2, ..., Document_n). When I press 'D', I get an error beep and nothing happens. Indeed some items are linked to a keytip, but I cannot navigate the list as described above.

We are developing some VSTO add-ins for Excel, Outlook, Powerpoint and Word for visually-impaired users. For each, we are creating a simplified ribbon that provides them with a subset of functionalities. For example:

<?xml version="1.0" encoding="UTF-8"?>

<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui"

  onLoad="Ribbon_Load">

    <ribbon startFromScratch="true">

        <tabs>

            <tab id="MainMenu" getLabel="GetMenuLabel" visible="true" keytip="M">

                <group id="FunctionsGroup" getLabel="GetGroupLabel">

                    <menu id="FileFunctions" keytip="F" getLabel="GetMenuLabel" >

                       <!--Action_1-->

                       <button id="Action_1"

                                getLabel="GetButtonLabel"

                                getImage="GetButtonImage"

                                getScreentip="GetScreenTip"

                                getSupertip="GetSuperTip"

                                onAction="OnActionButton" />

                        <!--Action_2-->

                        <button id="Action_2"

                                getLabel="GetButtonLabel"

                                getImage="GetButtonImage"

                                getScreentip="GetScreenTip"

                                getSupertip="GetSuperTip"

                                onAction="OnActionButton" />

                       <!--Action_N-->

                       <button id="Action_N"

                                getLabel="GetButtonLabel"

                                getImage="GetButtonImage"

                                getScreentip="GetScreenTip"

                                getSupertip="GetSuperTip"

                                onAction="OnActionButton" />

..........

                   </menu>

               </group>

            </tab>

        </tabs>

    </ribbon>

</customUI>

Having first letter navigation work in menus would be a major gain in terms of accessibility throughout all available Office menus (which there are hundreds and more shared between all Office apps).

My questions: 

1. Are there plans to support first letter navigation for menu components?
2. Is there a way we can attach key event handlers to UI components such as menus that are created from a ribbon.xml file?