Sets new QHTML contents in the object that complies with the syntax described in the
QHTML specification document.
HRESULT SetSourceText(BSTR source);
Parameters
source [in] - New QHTML contents compliant with the QHTML syntax.
Remarks
This function selects the current QHTML document based on the text string passed to the function. When called,
the values for properties Width, Height and HasBackgroundPicture become no longer valid, and their value can be updated
only by calling method RecalculateLayout. However, when trying to retrieve any of those values, if RecalculateLayout hasn't been
called since the last invocation of SetSourceText the QHTML parser will call method RecalculateLayout automatically
to guarantee their values always correspond to the current document.