How to keep the cell highlighted while editing

问题

I have a developed a custom drop-down renderer and drop-down cell editor. When the cell is highlighted by single clicking, the following css is applied to get the effect as shown in picture

.ag-cell:focus {
  border-radius: 5px;
  border: 2px solid blue !important;
}

I would like to have the same css on the cell when it is being edited by double clicking the cell. At present, the cell highlighting is missing as shown in the below image

来源：https://stackoverflow.com/questions/61821748/how-to-keep-the-cell-highlighted-while-editing