property ComboBox.Background(Part as BackgroundPartEnum) as Color
Returns or sets a value that indicates the background color for parts in the control. /*not supported in the lite version*/

TypeDescription
Part as BackgroundPartEnum A BackgroundPartEnum expression that indicates a part in the control.
Color A Color expression that indicates the background color for a specified part. The last 7 bits in the high significant byte of the color to indicates the identifier of the skin being used. Use the Add method to add new skins to the control. If you need to remove the skin appearance from a part of the control you need to reset the last 7 bits in the high significant byte of the color being applied to the background's part.
The Background property specifies a background color or a visual appearance for specific parts in the control. If the Background property is 0, the control draws the part as default. Use the Add method to add new skins to the control. Use the Remove method to remove a specific skin from the control. Use the Clear method to remove all skins in the control. Use the BeginUpdate and EndUpdate methods to maintain performance while init the control.  

The following VB sample changes the visual appearance for the drop down button. The sample uses the "" skin when the button is up, and uses the "" skin when the drop down button is down. 

With ComboBox1
    .VisualAppearance.Add 4, "D:\Temp\ExComboBox.Help\fbardd.ebn"
    .VisualAppearance.Add 5, "D:\Temp\ExComboBox.Help\fbarddd.ebn"
    .Background(exDropDownButtonUp) = &H4000000
    .Background(exDropDownButtonDown) = &H5000000
End With

The following C++ sample changes the visual appearance for the drop down button:

#include "appearance.h"
m_combobox.GetVisualAppearance().Add( 0x12, COleVariant( "D:\\Temp\\ExComboBox.Help\\fbardd.ebn" ) );
m_combobox.GetVisualAppearance().Add( 0x13, COleVariant( "D:\\Temp\\ExComboBox.Help\\fbarddd.ebn" ) );
m_combobox.SetBackground( 4 /*exDropDownButtonUp*/, 0x12000000 );
m_combobox.SetBackground( 5 /*exDropDownButtonDown*/, 0x13000000 );

The following VB.NET sample changes the visual appearance for the drop down button:

With AxComboBox1
    .VisualAppearance.Add(4, "D:\Temp\ExComboBox.Help\fbardd.ebn")
    .VisualAppearance.Add(5, "D:\Temp\ExComboBox.Help\fbarddd.ebn")
    .set_Background(EXCOMBOBOXLib.BackgroundPartEnum.exDropDownButtonUp, &H4000000)
    .set_Background(EXCOMBOBOXLib.BackgroundPartEnum.exDropDownButtonDown, &H5000000)
End With

The following C# sample changes the visual appearance for the drop down button:

axComboBox1.VisualAppearance.Add(4, "D:\\Temp\\ExComboBox.Help\\fbardd.ebn");
axComboBox1.VisualAppearance.Add(5, "D:\\Temp\\ExComboBox.Help\\fbarddd.ebn");
axComboBox1.set_Background(EXCOMBOBOXLib.BackgroundPartEnum.exDropDownButtonUp, 0x4000000);
axComboBox1.set_Background(EXCOMBOBOXLib.BackgroundPartEnum.exDropDownButtonDown, 0x5000000);

The following VFP sample changes the visual appearance for the drop down button:

with thisform.ComboBox1
    .VisualAppearance.Add(14, "D:\Temp\ExComboBox.Help\fbardd.ebn")
    .VisualAppearance.Add(15, "D:\Temp\ExComboBox.Help\fbarddd.ebn")
    .Background(4) = 234881024		&& exDropDownButtonUp
    .Background(5) = 251658240		&& exDropDownButtonDown
endwith