fix: switchKeyboardLayer

[eagleoflqj]

#1357
This seems a regression after 0.90.
Test case provides the new way to switch keyboard layer by shift.

[arnog]

Thanks for the PR. Could you tell me more about what was broken? How should I test this? BTW, as a side note, using the shift property is the recommended way to deal with multiple values for a key. Only use layers if you need a different layout (physical arrangement of the keycaps) between layers.

[eagleoflqj]

The problem with [shift] is that I can't release the key when I want it to take effect. It's not possible to use it on mobile phone with single hand.
So as you can see in the e2e test I added, I define a layout with 2 layers - one for lower letters and the other for upper letters. Press shift key to switch and no need to hold it.
The bug with switchKeyboardLayer is that it expects layer.dataset.layer to be the name of the layer. However with current mathlive, the element doesn't contain data-layer attribute as it did in 0.89. So

mathlive/src/virtual-keyboard/commands.ts

Line 17 in 2ba472e

if (layer.dataset.layer === layerName) {

doesn't work.
About how to test it, in any web page with a MathFieldElement, assign window.mathVirtualKeyboard.layouts as in the test case. The shift doesn't work in master's build, but works in this branch's build.

[arnog]

Oh, I see. OK, thanks for the explanation and for tracking this down. That's a good fix.

That said, it is a bug that the shift key when used with the shift property only works while pressed. It should also work as a toggle. I'll look into it.