Refactor sidebar

app/src/components/Sidebar/TopicPanel/TopicDeleteButton.tsx

@@ -0,0 +1,19 @@
+import * as q from '../../../../../backend/src/Model'
+import CustomIconButton from '../../helper/CustomIconButton'
+import Delete from '@material-ui/icons/Delete'
+import React from 'react'
+
+export const TopicDeleteButton = (props: {
+  node?: q.TreeNode<any>
+  deleteTopicAction: (node: q.TreeNode<any>) => void
+}) => {
+  const { node } = props
+  if (!node || !node.message || !node.message.value) {
+    return null
+  }
+  return (
+    <CustomIconButton onClick={() => props.deleteTopicAction(node)} tooltip="Clear this topic">
+      <Delete style={{ marginTop: '-3px' }} />
+    </CustomIconButton>
+  )
+}