How to control the visible of a widget?

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i want to control the visible or not of a widget, so i use a named is_visible field of data , and check the value before the layout and paint function. the is_visible is true, layout will return right size. this way is likely OK, but when the the visible widget is the Fled child of Flex , and the is_visible is false. the Flex container will leave over space of the invisible child. So, i want to know how to control the visible in druid correctly.

Start by examining how Flex handles child layout when the child’s is_visible value is false, including the layout and paint stages mentioned in the issue. Establish the expected behavior for an invisible child and determine how the parent should account for its size; the work is done when invisible Flex children no longer leave unintended space and the behavior is covered by an appropriate test.

Written by the indexing model from the issue text.