You can just make your own hot buttons texture and rename the button templates to whatever you want. Example =
<Ui2DAnimation item = "Mak_player_button_normal">
<Cycle>false</Cycle>
<Frames>
<Texture>Makaplayer.tga</Texture>
<Location>
<X>96</X>
<Y>224</Y>
</Location>
<Size>
<CX>23</CX>
<CY>23</CY>
</Size>
<Hotspot>
<X>0</X>
<Y>0</Y>
</Hotspot>
</Frames>
</Ui2DAnimation>
<Ui2DAnimation item = "Mak_player_button_pressed">
<Cycle>false</Cycle>
<Frames>
<Texture>Makaplayer.tga</Texture>
<Location>
<X>119</X>
<Y>224</Y>
</Location>
<Size>
<CX>23</CX>
<CY>23</CY>
</Size>
<Hotspot>
<X>0</X>
<Y>0</Y>
</Hotspot>
</Frames>
</Ui2DAnimation>
<Ui2DAnimation item = "Mak_player_button_flyby">
<Cycle>false</Cycle>
<Frames>
<Texture>Makaplayer.tga</Texture>
<Location>
<X>142</X>
<Y>224</Y>
</Location>
<Size>
<CX>23</CX>
<CY>23</CY>
</Size>
<Hotspot>
<X>0</X>
<Y>0</Y>
</Hotspot>
</Frames>
</Ui2DAnimation>
<Ui2DAnimation item = "Mak_player_button_pressed_flyby">
<Cycle>false</Cycle>
<Frames>
<Texture>Makaplayer.tga</Texture>
<Location>
<X>166</X>
<Y>224</Y>
</Location>
<Size>
<CX>23</CX>
<CY>23</CY>
</Size>
<Hotspot>
<X>0</X>
<Y>0</Y>
</Hotspot>
</Frames>
</Ui2DAnimation>
<Ui2DAnimation item = "Mak_player_button_disabled">
<Cycle>false</Cycle>
<Frames>
<Texture>Makaplayer.tga</Texture>
<Location>
<X>188</X>
<Y>224</Y>
</Location>
<Size>
<CX>23</CX>
<CY>23</CY>
</Size>
<Hotspot>
<X>0</X>
<Y>0</Y>
</Hotspot>
</Frames>
</Ui2DAnimation>
And you define it as a button template like so
<ButtonDrawTemplate>
<Normal>Mak_player_button_normal</Normal>
<Pressed>Mak_player_button_pressed</Pressed>
<Flyby>Mak_player_button_flyby</Flyby>
<Disabled>Mak_player_button_disabled</Disabled>
<PressedFlyby>Mak_player_button_pressed_flyby</PressedFlyby>
</ButtonDrawTemplate>
It works better doing it this way incase they ever have to update those window pieces file . Then you wont ever end up missing what they changed till you reedit the file to add in the changes they made.