I have posted on github, but it seems not a proper place to submit issue.
In the current sample, the splitcontainer can resize with real time resizing, which may cause performance problem when complex layouts were applied.
but for original gridsplitter, it has a ShowPreview property, which behaves "a translucent preview indicator follows your pointer while dragging. The actual resize is applied only when you release the mouse button. This can improve performance for complex layouts."
I searched the splitcontainer related API reference but not found the similar property, so can you consider to add this feature？
Best Regards.
