Improve robustness of tooltips with refined HoverBox positioning in 3.4.7

Author: krassowski

packages/jupyterlab-lsp/src/components/free_tooltip.ts

@@ -138,10 +138,18 @@ export class FreeTooltip extends Tooltip {
     const style = window.getComputedStyle(this.node);
     const paddingLeft = parseInt(style.paddingLeft!, 10) || 0;
 
+    // When the editor is attached to the main area, contain the hover box
+    // to the full area available (rather than to the editor itself); the available
+    // area excludes the toolbar, hence the first Widget child between MainAreaWidget
+    // and editor is preferred.
+    const host =
+      (editor.host.closest('.jp-MainAreaWidget > .lm-Widget') as HTMLElement) ||
+      editor.host;
+
     // Calculate the geometry of the tooltip.
     HoverBox.setGeometry({
       anchor,
-      host: editor.host,
+      host: host,
       maxHeight: MAX_HEIGHT,
       minHeight: MIN_HEIGHT,
       node: this.node,