Tool window Tab : Can I handle tool window tab click

What does "tab" mean in your case? Are "Project/Structure/Find/Run/Debug" tabs?

I am creating a tool window named 'Cloud" and each time when I click the window tab named "Cloud" , it should refresh the item inside it.

This code snippet may help you:

        ToolWindowManagerEx instanceEx = ToolWindowManagerEx.getInstanceEx(project);
        instanceEx.addToolWindowManagerListener(new ToolWindowManagerListener() {
          String lastActiveId = null;

          @Override
          public void toolWindowRegistered(@NotNull String s) {}

          @Override
          public void stateChanged() {
            String id = instanceEx.getActiveToolWindowId();
            if (!Comparing.equal(lastActiveId, id)) {
              lastActiveId = id;
              if ("Cloud".equals(id)) {
                //todo refresh the item
              }
            }
          }
        });

@Vassiliy Kudryashov Thanks a lot !