Adding Find\Filter functionality on Display method

Override Context method of Form control which is using display method and provide code for filter. E.g I have done below for PhysicalInvent field of InventOnHandItem form. 

void context()
{

int selectedMenu;
real test;
formrun fr;
Args ag;
Itemname strtext;
querybuilddataSource qb1;
queryrun qr;
query q;
PopupMenu menu = new PopupMenu(element.hWnd());
int a = menu.insertItem('Find');
int b = menu.insertItem('Filter');
int c = menu.insertItem('Remove Filter');


selectedMenu = menu.draw();

switch (selectedMenu)
{
case -1:
break;

case a:
ag = new args('SysformSearch');
fr = new formrun(ag);
fr.run();
fr.wait();
strtext = fr.design().controlName('FindEdit').valueStr();
if(strtext)
{
q = inventSum_Ds.query();
qb1 =q.dataSourceTable(tablenum(InventSum));
QB1.addRange(FieldNum(InventSum,PhysicalInvent)).value(SySQuery::value(strtext));
INVENTSUM_DS.query(Q);
INVENTSUM_ds.executeQuery();
}
break;

case b:
InventSum_DS.filter(FieldNum(InventSum,PhysicalInvent),Sysquery::value(InventSum.PhysicalInvent()));
break;

case c :
InventSum_DS.removeFilter();
break;

Default:
break;
}

}