Bug 213732

Description Stefan Mücke 2007-12-21 16:35:08 EST

Build ID: I20071213-1700
Eclipse 3.4 M4

When a hyperlink in a FormText is clicked, it fails when the FormText
is not completely visible and does not have the focus.

Steps to reproduce:

  - Open any .java file in Eclipse

  - Press F1 to open the help view and go to the "Related topics" page

  - Make sure that the top-most item of the "See also" items is not visible
    (resize the view so that not all items do fit; move the above or below
    another view to change its height)

  - Scroll to the bottom of the "See also" items list

  - Set focus on the Java editor again
	
  - Click on any item in the "See also" list

  - Result: the clicked link is not activated (executed), but instead
    FormText scrolls to the top and selects the top-most link

Problem description:

  The mouse click causes three events:

        - setFocus
        - mouseDown
        - mouseUp
	
  The events are fired in this order. The setFocus event comes first;
  it causes the first hyperlink in FormText to be selected. Since this
  hyperlink is not visible, it will be scrolled visible. Then the mouseDown
  event is handled. The mouse coordinates are those that caused the setFocus
  event. Thus they refer to the position before the FormText was scrolled,
  so that the correct link is selected.
  Finally, the mouseUp event occurs. This event is fired after the scrolling
  took place, so that the coordinates are different from those of the
  mouseDown event. No link activation is recognized.

  FormText already contains code that is supposed to handle focus gain
  caused by a mouse click. The FocusListener in FormText checks the field
  'mouseFocus' to handle the mouse focus. This field is supposed to be set
  to true when a 'mouseDown' event occurs. The problem, however, is that the
  setFocus event is always handled before the mouseDown event, and therefore
  mouseDown will always be false at this time.
  The processing order of the events cannot be changed, because WM_MOUSEACTIVATE
  comes before WM_LBUTTONDOWN (on Windows).

Solution idea:

  - disable scrolling on focusGained event
    (do not call method ensureVisible(...) in method handleFocusChange() )
  - call ensureVisible(...) only when a traverse event is processed