UX improvement: focus behavior after using shortcuts

[dj1020]

Since Posting provides convenient shortcuts such as c-o, asdk, and qwer,
I suggest improving the focus behavior after a shortcut is triggered.

For example, after pressing c-o then w, the cursor could automatically focus on the
request body content so it can be edited immediately (or I can press f4 to open the editor directly).

Currently, I still need to press j to move the focus to the edit area before I can
start editing.