淡入/淡出mediaElement顶部的堆栈面板（两者都在网格中的同一单元格内）

I am new to WPF and I am facing an issue in this. I am making a simple video application, and the application has 3 columns. The 2nd column is a gridsplitter, and the I am new to WPF and I am facing an issue in thi