1.to Hide dialogbox "PopUpProjectPick"

In order to hide the “PopUpProjectPick” dialogbox, first you need to obtain the object of the dialogbox then invoke the CloseDialog() method as shown in the following snippet code.

var dialog = ISGetObject("PopUpProjectPick");

dialog.CloseDialog();

2.to set values of focused row of "gvProjectPick" in webcombo "cbproject".

I suggest you to use the SetText() method of WebCombo in order to set the WebCombo value based on the selected row of “gvProjectPick”. Please obtain the object of “cbProject” WebCombo and then call the SetText() method as shown in the following.

var cbProject = ISGetObject("cbProject");

cbProject.SetText(ContactName.Value);

3.to make a callback of webgrid "gvRequisition" based on these values. (show data in "gvRequisition" based on these values)

I'm not quite sure how to help you with this requirement but you may try to use the "adding filter programmatically in WebGrid" approach.

Example:

function AddFilter()
{
    var grid = ISGetObject("WebGrid1");
    var newFilter = new WebGridFilter();

    newFilter.ColumnMember = "ContactName";
    newFilter.FilterType = "Like";
    newFilter.FilterText = "Ana";

    grid.RootTable.FilteredColumns.Add(newFilter);
    grid.RootTable.UpdateUI();
    grid.Refresh();
}