phantom line droppings

[Andy]

Hey folks, 

When I scroll down a page displayed as rich text in the radeditor using the mouse wheel, or by sliding the editor's scrollbar towards the bottom of the page, phantom line droppings appear over the text that scrolls up from the bottom of the editor's frame.  More precisely, numerous light grey 1pt thick horizontal lines are drawn across the text set at random intervals ranging from a few points to a couple of text lines apart.  As soon as I move the windows mouse pointer to outside of the radeditor's control boundaries, the lines disappear.  I've seen this behavior in other sites that use the telerik radeditor such as the forums in http://devhub.author-it.com/

As a user trying to key text into the control, I find this behavior most annoying because it obliterates the readability of almost everything being displayed, rendering the point of having such an editor available in the first place as being useless.  I have to spend time haphazardly scrolling the text up and down until I can get a clean display in which I can find the location of what I want to edit OR review.

As a developer, I'ld like to find a way to prevent these lines from ever appearing.  What's causing this problem and how can it be fixed?  It doesn't seem to happen when the editor is working with plain text.

I'm using Telerik RAD controls 2011.2.915.35 in visual studio C# build 91605-270-2201135-60151 and am viewing this on Internet Explorer 9  (9.0.8112.16421 with update version 9.0.3) on windows 7 SP1

this is some text
to scroll down on
so you can see the
phenomena happen
here as it seems
this is also a radeditor
telerik control (make
sure you are editing it
in the editor)

[Rumen]

Hi Andy,

Do you load large content in RadEditor? My recommendation is to try the suggestions provided in the following live demo: Working with large content.

My suggestion is to also test the editor by setting its ContentAreaMode property to DIV. Make sure that the ContentFilters property is set to None and that the Undo and Redo buttons are removed from the toolbar.

The content area of RadEditor is a standard editable IFRAME element and the reported problem sounds like a browser related problem due to insufficient hardware power.
This could be an add-on related problem. Could you please disable the add-ons of your IE9 browser and test again the editor. Please, also test the editor on another machine.

Do you experience under different browsers?

I was unable to reproduce the problem in the provided site because the page was not placed in edit mode and re wasn't an editor placed on it. You can see my test at: http://screencast.com/t/8s9vUYA8uhtT.

Best wishes,
Rumen
the Telerik team

[Andy]

You are right...the line artifacts are being produced by Internet Explorer 9 when it scrolls the textarea control (telerikeditorContentHiddenTextarea ) that is being used to display rad editor content.  The lines do NOT appear in google chrome. 

There isn't really a lot of content, however, I noticed there are a lot of escaped characters and perhaps the conversion of these is eating up time. Does the rad editor content in telerikeditorContentHiddenTextarea get copied to somewhere else on the client?

Andy

[Rumen]

Hi Andy ,

The hidden telerikeditorContentHiddenTextarea textarea has nothing to do with the editable iframe content area of RadEditor. The textarea is even hidden and could not be the reason for the problem. The hidden textarea is used to load content in the editable iframe content area as well as to send the editor's content when the page contents are submitted to the server and for this reason its contents are encoded.

Have you tried to test with DIV content area (ContentAreaMode="DIV") as well as to disable the content filters? Please also disable the stylesheet of the page?

You can even perform a test with the attached editable iframe HTML page and see whether the same behavior occurs on the problematic machine.

Best wishes,
Rumen
the Telerik team