Add tooltip if any in annotations layer

src/core/annotation.js

@@ -1366,6 +1366,7 @@ class ButtonWidgetAnnotation extends WidgetAnnotation {
 
     this.checkedAppearance = null;
     this.uncheckedAppearance = null;
+    this.data.isTooltipOnly = false;
 
     this.data.checkBox =
       !this.hasFieldFlag(AnnotationFieldFlag.RADIO) &&
@@ -1596,11 +1597,13 @@ class ButtonWidgetAnnotation extends WidgetAnnotation {
   }
 
   _processPushButton(params) {
-    if (!params.dict.has("A")) {
+    if (!params.dict.has("A") && !params.dict.has("TU")) {
       warn("Push buttons without action dictionaries are not supported");
       return;
     }
 
+    this.data.isTooltipOnly = !params.dict.has("A");
+
     Catalog.parseDestDictionary({
       destDict: params.dict,
       resultObj: this.data,

src/display/annotation_layer.js

@@ -165,6 +165,10 @@ class AnnotationElement {
     let width = data.rect[2] - data.rect[0];
     let height = data.rect[3] - data.rect[1];
 
+    if (this.data.alternativeText) {
+      container.setAttribute("title", this.data.alternativeText);
+    }
+
     container.setAttribute("data-annotation-id", data.id);
 
     // Do *not* modify `data.rect`, since that will corrupt the annotation
@@ -293,8 +297,10 @@ class LinkAnnotationElement extends AnnotationElement {
     const isRenderable = !!(
       parameters.data.url ||
       parameters.data.dest ||
-      parameters.data.action
+      parameters.data.action ||
+      parameters.data.isTooltipOnly
     );
+
     super(parameters, isRenderable);
   }
 
@@ -322,8 +328,10 @@ class LinkAnnotationElement extends AnnotationElement {
       });
     } else if (data.action) {
       this._bindNamedAction(link, data.action);
-    } else {
+    } else if (data.dest) {
       this._bindLink(link, data.dest);
+    } else {
+      this._bindLink(link, "");
     }
 
     this.container.appendChild(link);