Allow custom dialogs, better styling support.

Fix registration bug with tp-form.

tp-rtb-base-extension.js

@@ -6,6 +6,14 @@ export class TpRtbBaseExtension extends LitElement {
       :host {
         display: inline-block;
       }
+
+      slot::slotted(*) {
+        cursor: pointer;
+      }
+
+      :host([active]) slot::slotted(*) {
+        --tp-icon-color: var(--tp-rtb-action-active-color, currentColor);
+      }
       
       button {
         margin: 0 2px;
@@ -26,6 +34,16 @@ export class TpRtbBaseExtension extends LitElement {
     `;
   }
 
+  render() {
+    return html`
+      <slot @click=${this._handleClick}>
+        <button type="button" class="${this.active ? 'active' : ''}" title=${this.label} aria-label=${this.label}>
+          ${this.label}
+        </button>
+      </slot>
+    `;
+  }
+
   static get properties() {
     return {
       label: { type: String },
@@ -39,14 +57,6 @@ export class TpRtbBaseExtension extends LitElement {
     this.active = false;
   }
 
-  render() {
-    return html`
-      <button class="${this.active ? 'active' : ''}" @click=${this._handleClick}>
-        ${this.label}
-      </button>
-    `;
-  }
-
   connectedCallback() {
     super.connectedCallback();
     this._findParentEditor();