Adding a ToolTip for an Annotation

I am using Acrobat c++ sdk to develop my plugin. 
I need to create a ToolTip for an annotation. What I found is , Probably tooltip is not present as of now for an annotation. Although for ToolButton it is present.

To Implement , I ceated another annotation just beside my actual annotation and populated my data in that.
Binded two functions : MouseEnter and MouseExit to create and destroy the newly tool tip created annotation.

What I am trying is to run a thread, detach it, and in that thread , delele the annotation after two seconds. 

void RemoveToolTipAnnot(PDAnnot annot)
{
    AVDoc doc = AVAppGetActiveDoc();  // My program crashes here stating cannot access this .

    PDDoc pdDoc = AVDocGetPDDoc(doc);
    int pages = PDDocGetNumPages(pdDoc);

    bool found = false;
    for (int i = 0; i < pages; i++)
    {
        PDPage page = PDDocAcquirePage(pdDoc, i);
      ..........
      ..........

and this is main calling fn.

 pdPageDel = AVPageViewGetPage(pageView);

ASFixedRect rect, newToolTipRect;
PDAnnotGetRect(annot, &rect);

newToolTipRect.left = rect.right + Int16ToFixed(10);
newToolTipRect.top = rect.top + Int16ToFixed(10);
newToolTipRect.right = newToolTipRect.left + Int16ToFixed(100);
newToolTipRect.bottom = newToolTipRect.top - Int16ToFixed(30);

 tooltipAnnotDel =
    PDPageCreateAnnot(pdPageDel, ASAtomFromString("FreeText"), &newToolTipRect);

CosDoc cosDoc = CosObjGetDoc(PDAnnotGetCosObj(tooltipAnnotDel));
CosObj annotDict = PDAnnotGetCosObj(tooltipAnnotDel);

// Set tooltip text

CosObj co = PDAnnotGetCosObj(annot);
ASTCount cb;


string val = "";
if (CosDictKnownKeyString(co, TTC::DK_TTC_State))
{
    try
    {
        val = CosStringValue(CosDictGetKeyString(co, TTC::DK_TTC_State), &cb);
    }
    catch (...) {}
}

string data = "Annot Position:";
string d1 = data + val;
const char* str = d1.c_str();
CosObj contentsStr = CosNewString(cosDoc, false, (const  char*)str, strlen(str));
CosDictPut(annotDict, ASAtomFromString("Contents"), contentsStr);

// Set default appearance (DA)
const char* da = "0 0 1 rg /Helv 10 Tf";
CosObj daStr = CosNewString(cosDoc, false, (const  char*)da, strlen(da));
CosDictPut(annotDict, ASAtomFromString("DA"), daStr);

// Set color
PDColorValueRec color;
color.space = PDDeviceRGB;
color.value[0] = FloatToASFixed(1.0);
color.value[1] = FloatToASFixed(1.0);
color.value[2] = FloatToASFixed(0.8);
PDAnnotSetColor(tooltipAnnotDel, &color);

// Optional: make sure it's visible
PDAnnotSetFlags(tooltipAnnotDel, 0);

PDPageAddAnnot(pdPageDel, -2, tooltipAnnotDel);
   
PDPageNotifyContentsDidChange(pdPageDel);


PDPageRelease(pdPageDel);
thread t1(RemoveToolTipAnnot,tooltipAnnotDel);
t1.detach();

What is happening here?