Improve styling of error panel

[bampakoa]

Hey all! One of the areas that I think takes some improvement is the error panel. Whenever I see it in a forum question or Github issue, it feels a bit scary with its dark background 😄. In conjunction with the light color fonts, they create a high contrast situation that is not preserved very well.

I think that the error panel should take an overall re-styling that will be closer to Cesium colors (green, blue) and improve the user experience for users. If you think that this is a good idea, I would love to help with this and submit a suggestion PR.

[hpinkos]

Great suggestion @bampakoa! I don't think the themeing of that panel has ever been revisited

If you want to take a stab at it, I would be happy to review a PR! You can find the CSS here: https://github.com/CesiumGS/cesium/blob/master/Source/Widgets/CesiumWidget/CesiumWidget.css#L27

[bampakoa]

@hpinkos Thanks! Definitely I will do! How about exporting the showErrorPanel in a separate widget https://github.com/CesiumGS/cesium/blob/master/Source/Widgets/CesiumWidget/CesiumWidget.js#L606? Do you think this is feasible?

[hpinkos]

I'm not sure if that's entirely necessary since it's pretty much tied into the CesiumWidget. I think it's a better idea to start with a PR with just the styling changes so we don't have to worry about waiting for feedback on the other changes holding up the PR from being merged

[bampakoa]

@hpinkos here is a preview of the styling https://bit.ly/2VBca55.

I would also prefer the following:

1. Add a close (x) button at the top right corner
2. Convert the OK button to Copy to copy the error to the clipboard

[OmarShehata]

I like the idea of a copy - since that's often the common immediate next action, to report this error to someone (whether it's the application developer or opening an issue here).

I'm not sure about a close button or having "Ok" close the window - since that implies the application can carry on, but CesiumJS will only throw these errors when the application is an invalid state (as far as I'm aware). Sandcastle examples will use a window.alert for communicating if something is unsupported but when the application is allowed to carry on: https://sandcastle.cesium.com/index.html?src=3D%20Tiles%20Point%20Cloud%20Shading.html.

[bampakoa]

I'm not sure about a close button or having "Ok" close the window - since that implies the application can carry on

@OmarShehata

I agree with your point 😃 . This is a UX pattern that is generally followed in dialogs and pop-ups. It depends on the context of the error panel. If this is meant to be a dialog then maybe we should think to include both, a Cancel and a Close button.

Another aspect is that the user should be able to continue after an error occurs. Not necessarily in a fully functional state but maybe to reproduce a behavior 😉

[bampakoa]

@hpinkos it's been a while since this issue has been discussed. Do you have any additional thoughts on this?

[OmarShehata]

One thing I wanted to respond to here:

Another aspect is that the user should be able to continue after an error occurs. Not necessarily in a fully functional state but maybe to reproduce a behavior wink

I actually forgot that the current CesiumJS error panel is dissmissable, I almost never dismiss it because I think it's almost always been a fatal error in my experience. This makes me think we should have separate types of errors in the library, like warning dialogs that are dismissable and fatal errors that are not.

CesiumJS generally uses console logs for "one time warnings". What we do in Sandcastle for "dismissable warnings" is just window.alert(). I think improving this may be a separate effort but just wanted to note this down here for context.

[hpinkos]

@bampakoa I like your suggestions in #8739 (comment)

I would probably make the panel red though, so it reads more like an error. You can use #d69d93 for the background color and #510c00 for the text color

[hpinkos]

@OmarShehata If there's a runtime error that triggers this panel to appear, there should already be something logged to the console so we don't need to add anything else to handle that.

[bampakoa]

@hpinkos your suggestions look great! Thanks for the feedback 😃 I have made some adjustments that you can take a look here.

Notice that I have also added padding in the title of the error message so that it can stand up from the stack trace and be more easily distinguishable.

[hpinkos]

Looking good @bampakoa !

I would just make one change to make the whole panel the same color:

Could you open a pull request with your changes?

[bampakoa]

Sure @hpinkos 😀