我试图让一个DropdownButton显示在ListView中。尽管ListView代码位于另一个文件中，但此按钮是该ListView的直接子代。
尝试直接添加小部件不起作用，出现此错误：
I/flutter (22767): RenderIndexedStack object was given an infinite size during layout.
I/flutter (22767): This probably means that it is a render object that tries to be as big as possible, but it was put
I/flutter (22767): inside another render object that allows its children to pick their own size.
因此，我尝试将其放在一个简单的Column / Flexible组合中，不添加任何其他内容，因为这是我从Google看到的建议。
widgets.add(Column(children: [Flexible(child: subdropdown)],));
这给了我这个错误：
I/flutter (22767): RenderFlex children have non-zero flex but incoming height constraints are unbounded.
I/flutter (22767): When a column is in a parent that does not provide a finite height constraint, for example if it is
I/flutter (22767): in a vertical scrollable, it will try to shrink-wrap its children along the vertical axis. Setting a
I/flutter (22767): flex on a child (e.g. using Expanded) indicates that the child is to expand to fill the remaining
I/flutter (22767): space in the vertical direction.
I/flutter (22767): These two directives are mutually exclusive. If a parent is to shrink-wrap its child, the child
I/flutter (22767): cannot simultaneously expand to fit its parent.
I/flutter (22767): Consider setting mainAxisSize to MainAxisSize.min and using FlexFit.loose fits for the flexible
I/flutter (22767): children (using Flexible rather than Expanded). This will allow the flexible children to size
I/flutter (22767): themselves to less than the infinite remaining space they would otherwise be forced to take, and
I/flutter (22767): then will cause the RenderFlex to shrink-wrap the children rather than expanding to fit the maximum
I/flutter (22767): constraints provided by the parent.
然后，我尝试按照以下说明进行操作，并设置mainAxisSize和FlexFit只是恢复了原始错误。
widgets.add(Column(mainAxisSize: MainAxisSize.min, children: [Flexible(child: subdropdown, fit: FlexFit.loose)],));
我看过this线程，但是该线程具有下拉渲染某物，只是渲染不正确。我遇到的错误中断了渲染，因此它根本不显示任何内容。