Sample code for PanelStack using wrong variant of setState

[ChristianIvicevic]

While reading through the new sample code for the PanelStack component I noticed multiple calls to setState which seem to be wrong:

blueprint/packages/docs-app/src/examples/core-examples/panelStackExample.tsx

Line 49 in f29ca79

this.setState({ currentPanelStack: [newPanel, ...this.state.currentPanelStack] });

blueprint/packages/docs-app/src/examples/core-examples/panelStackExample.tsx

Line 55 in f29ca79

this.setState({ currentPanelStack: this.state.currentPanelStack.slice(1) });

If you need the current value of state while processing setState you should use the overload setState(previousState => ({/* ... */})) since the actual change of the state is not immediate.

[giladgray]

@ChristianIvicevic ah good catch. I suppose the current impl doesn't explode because these handlers are only called in response to user events, which happen rarely (not more than once per frame), but your proposal is the best practice.

mind submitting a PR? ⭐️

[ChristianIvicevic]

@giladgray Will do it later this weekend ⭐️