Merge pull request #6805 from lyft/xtinec--fix-sticky-tooltip

Fix sticky tooltips on nvd3 vizzes
diff --git a/superset/assets/src/visualizations/nvd3/utils.js b/superset/assets/src/visualizations/nvd3/utils.js
index 715b19e..92ac3dd 100644
--- a/superset/assets/src/visualizations/nvd3/utils.js
+++ b/superset/assets/src/visualizations/nvd3/utils.js
@@ -166,9 +166,9 @@
 }
 
 export function hideTooltips() {
-  const target = document.querySelector('.nvtooltip');
-  if (target) {
-    target.style.opacity = 0;
+  const targets = document.querySelectorAll('.nvtooltip');
+  if (targets.length > 0) {
+    targets.forEach(t => t.remove());
   }
 }