I create two B4XComboBoxes in the constructor.
I give them equal properties. For B4XComboBox1 in the constructor, for B4XComboBox2 at runtime:
B4X:
Sub Activity_Create(FirstTime As Boolean)
Activity.LoadLayout("Layout")
B4XComboBox2.cmbBox.Background=setGradientDrawable
End Sub
Sub setGradientDrawable As GradientDrawable
Dim gr As GradientDrawable
Dim cls(2) As Int
cls(0)=Colors.ARGB(255,124,245,239)
cls(1)=Colors.ARGB(255,13,142,137)
gr.Initialize("TOP_BOTTOM",cls)
gr.CornerRadius=8
Return gr
End Sub