✨ Synchronise modifiers on physical and virtual kb

Close #440

src/classes/keyboard.class.js

@@ -226,6 +226,13 @@ class Keyboard {
         this.keydownHandler = e => {
             // See #330
             if (e.getModifierState("AltGraph")) return;
+
+            // See #440
+            if (e.code === "ShiftLeft" || e.code === "ShiftRight") this.container.dataset.isShiftOn = true;
+            if (e.code === "AltLeft" || e.code === "AltRight") this.container.dataset.isAltOn = true;
+            if (e.code === "CapsLock" && !this.container.dataset.isCapsLckOn) this.container.dataset.isCapsLckOn = true;
+            if (e.code === "CapsLock" && this.container.dataset.isCapsLckOn) this.container.dataset.isCapsLckOn = false;
+
             let key = findKey(e);
             if (key === null) return;
             if (key.length) {
@@ -243,6 +250,11 @@ class Keyboard {
         document.onkeyup = e => {
             // See #330
             if (e.key !== "AltGraph" && e.getModifierState("AltGraph")) return;
+
+            // See #440
+            if (e.code === "ShiftLeft" || e.code === "ShiftRight") this.container.dataset.isShiftOn = false;
+            if (e.code === "AltLeft" || e.code === "AltRight") this.container.dataset.isAltOn = false;
+
             let key = findKey(e);
             if (key === null) return;
             if (key.length) {