Finally, I ended up with following approach:
$oDocument=_UIA_getFirstObjectOfElement($oIE,$cDocumentWindow, $treescope_subtree)
If not isobj($oDocument) Then
_UIA_DumpThemAll($oIE,$treescope_subtree)
Else
$t=stringsplit(_UIA_getPropertyValue($oDocument, $UIA_BoundingRectanglePropertyId),";")
_UIA_DrawRect($t[1],$t[3]+$t[1],$t[2],$t[4]+$t[2])
;~loop until button is loaded
local $oClock =_UIA_getFirstObjectOfElement($oDocument,"id:=TodaysActivities_btnClock", $treescope_subtree)
While not IsObj($oClock)
Sleep(500)
$oClock =_UIA_getFirstObjectOfElement($oDocument,"id:=TodaysActivities_btnClock", $treescope_subtree)
WEnd
_UIA_action($oClock,"leftclick")
Sleep(2000)
_UIA_action($oIE,"close")
EndIf
I put "while" cycle to check if needed button is loaded. It seems like it is working...
If anyone has better ideas - please welcome to share it... :-)