message: Choose a visible panel. Invisible panels are suspended.
diff: @@ -15,12 +15,12 @@ export class HoverProvider implements vscode.HoverProvider {
  return new Promise((resolve, _reject) => {
  const configuration = vscode.workspace.getConfiguration('latex-workshop')
  const hov = configuration.get('hoverPreview.enabled') as boolean
  - if (hov && this.extension.panels.length > 0) {
  + const panel = this.extension.panels.filter( p => p.visible )[0]
  + if (hov && panel !== undefined) {
  const tr = this.findHoverOnTex(document, position)
  if (tr) {
  const scale = configuration.get('hoverPreview.scale') as number
  const [tex, range] = tr
  - const panel = this.extension.panels[0]
  const d = panel.webview.onDidReceiveMessage( message => {
  resolve( new vscode.Hover(new vscode.MarkdownString( '![equation](' + message.dataurl + ')' ), range ) )
  d.dispose()
  