How do you get the background colour of a textbox,cell ,dropdown?

This is a VBScript example. It will return a RGB value of the one pixel at the coordinate of the object that you pass to the function.

Function Return_RGB(objWindowType, nvXcoord, nvYcoord)
******************************************************************************************
'*    FUNCTION: Return_RGB(objWindowType As Object, nvXcoord As Long, nvYcoord As Long)
'*
'*    PURPOSE: To return a RGB set of values that is the color of the X, Y coordinate of the Window Object
'*
'*    EXAMPLE: Return_RGB(Sys.Process("MyProcess").VCLObject("frmMain"), 10, 10) Normal Window object
'*
'*    The example returns the RGB color of the pixel at the 10,10 coordinate of the Sys.Process("MyProcess").VCLObject("frmMain") object.
'*    The return value is a string that would look like >>> 255,26,0
'*    The '255' is the Red value. 1st position
'*    The '26' is the Green value. 2nd position
'*    The '0' is the Blue value. 3rd position
'*
'*    Last Update: 02-27-2014 - TEB - Converted to TestComplete script.
'*                          05-01-2009 - TEB - Created
'******************************************************************************************
Dim tPOS, dcWindow, nvRGB, svTemp
Dim lRed, lGreen, lBlue

Set tPOS = POINTAPI
Return_RGB = "NO COLOR FOUND"

If objWindowType.Exists = True Then

    ' Move to the X, Y coordinate
    objWindowType.HoverMouse nvXcoord, nvYcoord
    ' Get the dc of a specific hwnd - the desktop
    dcWindow = Win32API.GetWindowDC(0)
    ' Get the cursor position relative to the screen.
    tPOS.y = objWindowType.ScreenTop + nvYcoord
    tPOS.x = objWindowType.ScreenLeft + nvXcoord

    ' Use GetPixel() with the appropriate DC and location
    nvRGB = Win32API.GetPixel(dcWindow, tPOS.x, tPOS.y)
 
    ' HEX to string
    svTemp = Right("000000" & Hex(nvRGB), 6)

    ' Parse out the individual values
    lRed = CLng("&H" & Right(svTemp, 2))
    lGreen = CLng("&H" & Mid(svTemp, 3, 2))
    lBlue = CLng("&H" & Left(svTemp, 2))

    Return_RGB = CStr(lRed) & "," & CStr(lGreen) & "," & CStr(lBlue) 'Return the RGB values here

Else
    Return_RGB = "NO COLOR FOUND"
    Log.Warning "Return_RGB - NO COLOR FOUND - Object did not exist - Window to check= " & objWindowType.Name
End If

End Function
 
Almost forgot.......You will need these functions to define the POINTAPI class
 
Class classPOINTAPI
    ' Used in Function Return_RGB
    Public x
    Public y
End Class
 
Function POINTAPI
    Set POINTAPI = New classPOINTAPI
End Function