How to auto scale widget when you click some button to let some widget popup?

[wade0608]

I want to let my layout change when I clicked the button.
There is a horizontal box in the bottom of my layout and the right hand side is the sidebar menu.
And then, I hope the horizontal box will scale when I chick the button to expand the sidebar menu. How can I do, must use animation?
First pics:

The result I wanted:
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[Everynone]

Just dropping a link, answered here:

How to create sidebar?

add the border and the panel to a horizontal box, you can use another horizontal box inside the border to house other items. Or replace the border with just a horizontal box if no background is needed. The example you have a is a bit unclear. the wPanel is set to auto size the horizontal box in the canvas no longer Sizes To Content (see previous posts) - the desired functionality changed since the first post request the size box here may not be needed if you fill the border with some other cont…

If you want this done with a button, call the script that’s shown on button click, either instead or in addition to.