If the splitter container has 100%, the height of the Splitter panes is changed when the splitbar is moved to the right or left.
The panes of the splitter have the wrong height when it is moved to the left and the correct one when it is moved to the right.
Splitbar panes should have the same height regardless of splitbar moving.
When the splitbar is moved to the left, the left position of the second splitbar pane should be updated before its width. For now, it is updated after it, which causes showing a horizontal scrollbar of the Splitter parent for a moment. As result, the Splitter pane height is calculated wrongly.
Currently, attributes of an initial element are copied to a dynamically created outer element. This behavior is common for widgets from the "Editors" group (and not only). This causes multiple confusing results as applying styles or classes to the outer and inner elements at the same time. For example in this Dojo sample, when width or height is defined by percentage units, this causes a broken appearance.
Consider removing such attributes from the initial element and keeping them only on the generated outer one. A similar issue is caused when a custom class is applied to the initial element. The class is applied to both elements (outer and inner), so an additional selector should be used to target an exact element.