1）您是说DropDown的DropDownStyle吗？

1) Do you mean DropDownStyle of DropDown? This is the setting which enables user input.

2）变形是什么意思-您在哪里看到它？

2) What do you mean by 'deformed' - and where are you seeing this?

编辑：如果此OnDrawItem调用是为了渲染顶部框-e.State设置了ComboBoxEdit位标志。

If this OnDrawItem call is to render the top box - e.State has the ComboBoxEdit bit flag set. Check for this to render differently.

if( (e.State & DrawItemState.ComboBoxEdit) != DrawItemState.ComboBoxEdit ) 
{
    // Do drawing logic just for the top edit part
}
else
{
    // Draw logic here for rendering in the drop-down
}