When you use the following code, all text input boxes are narrowed when you click the text box. Just like this, just...
B4X:
Private gdwGradient As GradientDrawable
Private cols(2) As Int
Private cdwColor As ColorDrawable
cols(0) = Colors.ARGB(255,100,255,255)
cols(1) = Colors.Transparent
gdwGradient.Initialize("TOP_BOTTOM", cols)
gdwGradient.CornerRadius = 5
spnUnittype.Background = gdwGradient
cdwColor.Initialize(Colors.ARGB(255,255,255,255), 0dip)
edtInput.Background = cdwColor
edtOutput.Background = cdwColor
spnInput.Background = cdwColor
spnOutput.Background = cdwColor
spnUnittype.DropdownBackgroundColor = Colors.ARGB(255,200,255,255)
spnInput.DropdownBackgroundColor = Colors.ARGB(255,255,255,200)
spnOutput.DropdownBackgroundColor = Colors.ARGB(255,255,255,200)