<Swing Dev> [9] Review request for 8027639: JComboBox's popup leaves tracks after closing

[Semyon Sadetsky]

On 24.11.2016 21:11, Sergey Bylokhov wrote:
> On 24.11.16 20:42, Semyon Sadetsky wrote:
>>> It have a different implementations because it has different meaning:
>>>  - The non-opaque window is a window which uses transparent background.
>>>  - The non-opaque component is the component which require the parents
>>> be painted first. it is not necessary that the background in this case
>>> should be transparent(It is possible that the component draw something
>>> only in some place of its bounds) And transparent color is not always
>>> requires that the component should be non-opaque, because components
>>> can ignore its background.
>> Hmm.. Both JComponent and Window override the same Component.isOpaque()
>> but the property has different meaning for each of them.
>
> The requirements for Window.isOpaque() are a subset of 
> JComponent.isOpaque(). Because the Window does not have the parents, 
> which should/shouldn't be painted. And to be a transparent the Window 
> must have a transparent color. Both of these cases are not applicable 
> to the components.
Having opaque property regulated by user for per-pixel translucency is a 
mistake because the painted result of the translucent and opaque 
component will depend on the platform, the used buffer type and the pipe.
>
>> Probably, this is a design mistake?
>
> This is how it was implemented long time ago.
It is a good chance to fix the bug at last.