Proposal for the functionality of footerItems and variable sidebar width

[ZhongGuanbin]

Is your feature request related to a problem? Please describe. The width of the current sidebar is fixed, and when setting footerItems, the length ratio of footerItems to items will be 1:1

Describe the solution you'd like I hope to achieve variable sidebar width and free height setting for footItems and items

Describe alternatives you've considered As shown in the following figure Obtain layout information through GestureDetector or other components to achieve variable sidebar width; Due to both items and footItems using Expanded, the height ratio will be 1:1 by default. Therefore, the above requirements can be achieved by releasing the flex parameter or fixing the height of footItems