fix broken style for ubuntu
fix a conflicting shortcut "D"

- "D" is used for delete action
- open and download have the same place and open has a shortcut key "O"
- this will tell download action to use shortcut key "O" as well
Merge pull request #348 from haiwen/fix_conflict_shortcuts

fix a conflicting shortcut "D"
Merge pull request #347 from haiwen/fix_broken_style_for_ubuntu

fix broken style for ubuntu
remove debug prints
try to open cached file if the file is cached previously