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Frequently Asked Question #1
Question: My menus seem unable to cover form elements, Flash, and Java
applets, and IFrames, that exist below them in z-order. The form elements always show through! This
behavior is common to all form elements in Navigator, but only the
<select> element in Explorer. The problem persists no matter how I set
the z-index of the form or its elements. Why?
Answer: The persistence of form element and Flash/Java applet/IFrame visibility
is not affected by the z-order of in-page positioned elements. This behavior is documented by
the browser vendors, and there is little we can do to avoid it.
You can read about the problem, illustrated with many in-page examples at the
DHTML Diner: Positioned Elements and OS Controls, Applets and Plug-ins
HierMenus work arounds primarily take one of two possible approaches:
Hide the form elements/applets when the menus are displayed, and restore them
when the menus are hidden.
Use an iframe mask between the menus and the element
(this technique works only in Internet Explorer 5.5/6).
Page elements can be hidden by way of the HM_f_ToggleElementList function
included in the HierMenus 6 HM_Loader.js file, used in combination with the
TopUponDisplay, ChildUponDisplay, TopUponHide, and
ChildUponHide parameters. Further information pertaining to each of these
components can be found at these links:
Bulletin 6: HM_f_ToggleElementList
TopUponHide
TopUponDisplay
ChildUponHide
ChildUponDisplay
The Internet Explorer only IFRAME masking technique can be utilized by way of the
HM_f_IEMaskCreate, HM_f_IEMaskToggle, and HM_f_IEMaskMove
methods included in the HM_Loader.js file. Further description of these
functions and how to implement them can be found at these links:
Using the Custom Code in HM_Loader.js
HM_OnMove
HM_OnVisibilityToggle
HM_OnMenuCreated
Finally, for Flash applets in particular, you may also want to have a look at
Macromedia's own documentation on the subject:
http://www.macromedia.com/support/flash/ts/documents/wmode.htm
http://www.macromedia.com/support/flash/ts/documents/flash_top_layer.htm
This question is also addressed as Known Issue #1 on our
known issues list.
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