ModelProject/Library/PackageCache/com.unity.2d.animation@5.1.1/Editor/Assets/SkinningModule/BoneToolbar.uxml

<?xml version="1.0" encoding="utf-8"?>
<UXML xmlns:ui="UnityEngine.UIElements" xmlns:aui="UnityEditor.U2D.Animation">
  <aui:BoneToolbar name="BoneToolbar">
      <ui:PopupWindow name="PopupWindow" text="Bones">
          <ui:Button name="EditPose" tooltip="Pose character to view setup">
              <ui:Image name="EditPoseImage" />
              <ui:Label text ="Preview Pose"/>
          </ui:Button>
          <ui:Button name="EditJoints" tooltip="Edit bones position and rotation">
              <ui:Image name="EditJointsImage" />
              <ui:Label text ="Edit Bone"/>
          </ui:Button>
          <ui:Button name="CreateBone" tooltip="Create new bones">
              <ui:Image name="CreateBoneImage" />
              <ui:Label text ="Create Bone"/>
          </ui:Button>
          <ui:Button name="SplitBone" tooltip="Split an existing bone">
              <ui:Image name="SplitBoneImage" />
              <ui:Label text ="Split Bone"/>
          </ui:Button>
      </ui:PopupWindow>
  </aui:BoneToolbar>
</UXML>