Outlook AddIn - how to show command button on TabDefault ?

[b-tosic]

I'm developing Outlook AddIn and I have a taskpane for MessageReadCommandSurface with one button. That works fine in Outlook Windows Desktop Classic, I see button on the ribbon. However, on outlook webmail (i.e. https://outlook.office.com/) button is not obviously there. User has to click on the "Apps" button and then it is there. But, I can see that some addins like ScriptLab and VivaInsights have buttons just next to the Reply/ReplyAll... buttons. How can we also achieve that?

Here is the excerpt from my manifest.xml:

<ExtensionPoint xsi:type="MessageReadCommandSurface">
              <OfficeTab id="TabDefault">
                <Group id="group.TB.MessageRead">
                  <Label resid="residGroupLabel"/>
                  <Control xsi:type="Button" id="btnShowTaskpaneTBRead">
                    <Label resid="residBtnLabelTB"/>
                    <Supertip>
                      <Title resid="residBtnLabelTB" />
                      <Description resid="residSupertipDescTB" />
                    </Supertip>
                    <Icon>
                      <bt:Image size="16" resid="Icon.16x16" />
                      <bt:Image size="32" resid="Icon.16x16" />
                      <bt:Image size="80" resid="Icon.16x16" />
                    </Icon>
                    <Action xsi:type="ShowTaskpane">
                      <SourceLocation resid="Trackingpane.Url"/>
                    </Action>
                  </Control>
                </Group>
              </OfficeTab>
            </ExtensionPoint>

How does ScriptLab put a button (or Menu button) here ?

[b-tosic]

One workaround that we found is that there is a "Pin" option on right click (Apps->Our AddIn->Right Click).
That will pin the icon (not the task pane itself) and then Icon will show next to the ScriptLab icon.
Just to mention: our taskpane is not pinnable (and we don't want it to be pinnable) so, deliberately, we don't have SupportsPinning for it in manifest.

Question is: can we do this programaticaly from OfficeJS or somehow in manifest.xml?