// preload button home
bth1_off = new Image(); 
bth1_off.src="_gfx/bth_section1_off.jpg";
bth1_on = new Image(); 
bth1_on.src="_gfx/bth_section1_on.jpg";
bth2_off = new Image(); 
bth2_off.src="_gfx/bth_section2_off.jpg";
bth2_on = new Image(); 
bth2_on.src="_gfx/bth_section2_on.jpg";

// preload button internal
bt1_off = new Image(); 
bt1_off.src="_gfx/bt_section1_off.jpg";
bt1_on = new Image(); 
bt1_on.src="_gfx/bt_section1_on.jpg";
bt2_off = new Image(); 
bt2_off.src="_gfx/bt_section2_off.jpg";
bt2_on = new Image(); 
bt2_on.src="_gfx/bt_section2_on.jpg";
bt3_off = new Image(); 
bt3_off.src="_gfx/bt_section3_off.jpg";
bt3_on = new Image(); 
bt3_on.src="_gfx/bt_section3_on.jpg";
bt4_off = new Image(); 
bt4_off.src="_gfx/bt_section4_off.jpg";
bt4_on = new Image(); 
bt4_on.src="_gfx/bt_section4_on.jpg";