I need to hide buttons from form header from Portal Users, but I want to leave the Statusbar widget visible. In the view I've added spans for buttons and status field like this:

<header class="oe_header">
     <span attrs="{'invisible': [('is_portal_user','=',True)] }">
         <button name="case_open_do_mnie" string="Open" type="object" class="oe_highlight" states="draft"  />
         <button name="make_issue" string="Make Issue" type="object" class="oe_highlight" states="open,answer"  />
     <button name="case_close" string="Close Case" type="object" states="draft,answer,open"  />
     <button name="case_close" string="Close Case" type="object" states="resolved" class="oe_highlight"  />
     <button name="case_reset" string="Reset to Draft" type="object" states="cancel,done"  />
     <button name="case_cancel" string="Cancel Case" type="object" states="open,issue,answer,resolved,done"  />
</span>
<span>
        <field name="state" nolabel="1" widget="statusbar" statusbar_visible="draft,open,done" 
                            statusbar_colors='{"open":"blue", "issue":"blue", "answer":"blue", "resolved":"red", "done":"blue"}'                            
    /> 
</span>

</header>

But it resulted in bad formatted header line (see picture below) - status bar is cropped. Is there a way to hide the buttons from header and preserve right height of header line for status bar?