I added the following code to Mook's 3/4 hotbar mod and it works perfectly. This is just what I noticed that was different between his and the default. I'm no UI modder and don't pretend to be so don't blame me if anything goes wrong.
I have also attached the modded file if you would like to use it.
Code:
<Page AbsorbsInput="false" Location="3,10" Name="BankPage" PackLocation="left,center" PackLocationProp="0003/0001,-019/0001" RStyleDefault=" " ScrollExtent="21,42" Size="21,42">
<RectangleStyle Center="arrow_down" CenterShrinkH="true" CenterShrinkV="true" EastShrink="true" Name="rs_down" North="drop_down_top" NorthShrink="true" South="drop_down_bottom" SouthShrink="true" WestShrink="true"/>
<RectangleStyle Center="arrow_up" CenterShrinkH="true" CenterShrinkV="true" EastShrink="true" Name="rs_up" North="drop_down_top" NorthShrink="true" South="drop_down_bottom" SouthShrink="true" WestShrink="true"/>
<ButtonStyle DisabledTextColor="#A0A0A0" MouseOverTextColor="#FFFF00" Name="bs_down" RStyleDefault="rs_down"/>
<ButtonStyle DisabledTextColor="#A0A0A0" MouseOverTextColor="#FFFF00" Name="bs_up" RStyleDefault="rs_up"/>
<Text AbsorbsInput="false" Color="#F0D0A0" Font="/TextStyles.Normal.NormalStyle" LocalText="1" Location="0,12" Name="CurrentBank" ScrollExtent="23,17" ShadowStyle="/ShadowStylesNew.OutlineDrop.style" Size="23,17" TextAlignment="Center" UserMovable="true" UserResizable="true">1</Text>
<Button LocalText="Up" LocalTooltip="Previous Bank" Location="3,27" Name="UpArrow" ScrollExtent="15,15" Size="15,15" Style="bs_down" Tooltip="Previous Bank">Up</Button>
<Button LocalText="Dn" LocalTooltip="Next Bank" Location="3,0" Name="DownArrow" ScrollExtent="15,15" Size="15,15" Style="bs_up" Tooltip="Next Bank">Dn</Button>
<ImageStyle Filter="true" Name="arrow_down">
<ImageFrame Name="image" Source="images/buttons_master.dds" SourceRect="32,190,49,209"/>
</ImageStyle>
<ImageStyle Filter="true" Name="arrow_up">
<ImageFrame Name="image" Source="images/buttons_master.dds" SourceRect="32,216,49,235"/>
</ImageStyle>
</Page>