[spiel2001]

I am not sure if setting the OnShow script might not cause a taint problem. It might be better to just reparent them to nUI.BlizUI

It's kind of an edge use-case to change it in nUI5, but I'll be sure to include an option in nUI6 and you can do a simple edit in nUI or use a macro to do it in the meantime.

The edit is very easy... open [ Interface > AddOns > nUI > Bars > nUI_ButtonBar.lua ] and locate the statement "if bar:GetName() == "nUI_ActionBar" then" at line 855 and make the following two highlighted changes...

if bar:GetName() == "nUI_ActionBar" then
  
        ActionBarUpButton:SetParent( nUI.BlizUI );
        ActionBarUpButton:SetFrameStrata( bar:GetFrameStrata() );
        ActionBarUpButton:SetFrameLevel( bar:GetFrameLevel() );
        ActionBarUpButton:SetScale( 1.5 * nUI.vScale );
        ActionBarUpButton:ClearAllPoints();
        ActionBarUpButton:SetPoint( "TOPLEFT", bar, "TOPRIGHT", -10 * nUI.hScale, 12 * nUI.vScale );
        ActionBarUpButton:Show();
    
        ActionBarDownButton:SetParent( nUI.BlizUI );
        ActionBarDownButton:SetFrameStrata( bar:GetFrameStrata() );
        ActionBarDownButton:SetFrameLevel( bar:GetFrameLevel() );
        ActionBarDownButton:SetScale( 1.5 * nUI.vScale );
        ActionBarDownButton:ClearAllPoints();
        ActionBarDownButton:SetPoint( "BOTTOMLEFT", bar, "BOTTOMRIGHT", -10 * nUI.hScale, -12 * nUI.vScale  );
        ActionBarDownButton:Show();
        
    end

That should do the trick.

If you want to use a macro, just do this...

/script ActionBarUpButton:SetParent( nUI.BlizUI ); ActionBarDownButton:SetParent( nUI.BlizUI );