public FlatComboAdapter(ComboBox comboBox, bool smallButton)
            {
                // adapter is re-created when combobox is resized, see IsValid method, thus we don't need to handle DPI changed explicitly
                s_offsetPixels = comboBox.LogicalToDeviceUnits(OFFSET_2PIXELS);

                _clientRect = comboBox.ClientRectangle;
                int dropDownButtonWidth = SystemInformation.GetHorizontalScrollBarArrowWidthForDpi(comboBox._deviceDpi);

                _outerBorder      = new Rectangle(_clientRect.Location, new Size(_clientRect.Width - 1, _clientRect.Height - 1));
                _innerBorder      = new Rectangle(_outerBorder.X + 1, _outerBorder.Y + 1, _outerBorder.Width - dropDownButtonWidth - 2, _outerBorder.Height - 2);
                _innerInnerBorder = new Rectangle(_innerBorder.X + 1, _innerBorder.Y + 1, _innerBorder.Width - 2, _innerBorder.Height - 2);
                _dropDownRect     = new Rectangle(_innerBorder.Right + 1, _innerBorder.Y, dropDownButtonWidth, _innerBorder.Height + 1);

                // fill in several pixels of the dropdown rect with white so that it looks like the combo button is thinner.
                if (smallButton)
                {
                    _whiteFillRect       = _dropDownRect;
                    _whiteFillRect.Width = WhiteFillRectWidth;
                    _dropDownRect.X     += WhiteFillRectWidth;
                    _dropDownRect.Width -= WhiteFillRectWidth;
                }

                _origRightToLeft = comboBox.RightToLeft;

                if (_origRightToLeft == RightToLeft.Yes)
                {
                    _innerBorder.X      = _clientRect.Width - _innerBorder.Right;
                    _innerInnerBorder.X = _clientRect.Width - _innerInnerBorder.Right;
                    _dropDownRect.X     = _clientRect.Width - _dropDownRect.Right;
                    _whiteFillRect.X    = _clientRect.Width - _whiteFillRect.Right + 1; // since we're filling, we need to move over to the next px.
                }
            }