Make editable hide correctly when activating codable

ts/editor/codable.ts

@@ -5,10 +5,10 @@ import * as CodeMirror from "codemirror/lib/codemirror";
 import "codemirror/mode/htmlmixed/htmlmixed";
 
 const codeMirrorOptions = {
-    lineNumbers: true,
-    lineWrapping: true,
     mode: "htmlmixed",
     theme: "monokai",
+    lineNumbers: true,
+    lineWrapping: true,
 };
 
 const parser = new DOMParser();
@@ -26,15 +26,15 @@ export class Codable extends HTMLTextAreaElement {
         this.setAttribute("hidden", "");
     }
 
-    toggle(html: string): string {
-        return this.codeMirror ? this.teardown() : this.setup(html);
-    }
-
-    setup(html: string): string {
+    setup(html: string): void {
         this.active = true;
         this.value = html;
         this.codeMirror = CodeMirror.fromTextArea(this, codeMirrorOptions);
-        return "";
+    }
+
+    focus(): void {
+        this.codeMirror.focus();
+        this.codeMirror.setCursor(this.codeMirror.lineCount(), 0);
     }
 
     teardown(): string {

ts/editor/editable.scss

@@ -40,3 +40,7 @@ img.drawing {
         filter: unquote("invert() hue-rotate(180deg)");
     }
 }
+
+[hidden] {
+    display: none;
+}

ts/editor/editingArea.ts

@@ -10,6 +10,7 @@ import type { Codable } from "./codable";
 
 import { updateActiveButtons } from "./toolbar";
 import { bridgeCommand } from "./lib";
+import { caretToEnd } from "./helpers";
 import { onInput, onKey, onKeyUp } from "./inputHandlers";
 import { onFocus, onBlur } from "./focusHandlers";
 
@@ -126,10 +127,29 @@ export class EditingArea extends HTMLDivElement {
         this.editable.blur();
     }
 
+    hasFocus(): boolean {
+        return document.activeElement === this;
+    }
+
     toggleHtmlEdit(): void {
-        const output = this.codable.toggle(this.fieldHTML);
-        if (output) {
-            this.fieldHTML = output;
+        const hadFocus = this.hasFocus();
+
+        if (this.codable.active) {
+            const html = this.codable.teardown();
+            this.fieldHTML = html;
+
+            this.editable.hidden = false;
+            if (hadFocus) {
+                this.focusEditable();
+                caretToEnd(this);
+            }
+        } else {
+            this.editable.hidden = true;
+            this.codable.setup(this.fieldHTML);
+
+            if (hadFocus) {
+                this.codable.focus();
+            }
         }
     }
 }