Describe the bug
Scenario: a Window appended to the content of a TabStrip tab. If the content is scrolled down, when you open the Window it does not appear centered. Reproducible only with the SASS themes.

To reproduce
Steps to reproduce the behavior:

1. Go to this dojo example: https://dojo.telerik.com/unopUDaQ/7
2. Follow the instructions in tab 1: scroll down to the bottom of the tab's content and click the button.
3. The Window shows up, but it is not centered. In Chrome the tab's content is automatically scrolled up a little bit.
4. On dragging the Window, the mouse cursor is offset from the title.

Expected behavior
The behavior with the LESS themes is the expected one. The Window appears centered and there is no offset when dragging it.

Affected package (please remove the unneeded items)

• theme-default
• theme-bootstrap
• theme-material

Affected suites (please remove the unneeded items)

• Kendo UI for jQuery

Affected browsers (please remove the unneeded items)

• All

Build system information (please remove the unneeded items)

• Not Applicable