我无法在笔记本电脑和 PC 中启用锁屏模式。我去了系统设置 > 屏幕 > 锁定 Ctrl+Alt+L ：没有任何反应！捷径在那里，但不起作用！
sudo apt-get --reinstall install gnome-screensaver :
Reading package lists... Done
Building dependency tree
Reading state information... Done
You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies:
dassault-systemes-draftsight:i386 : Depends: sendmail:i386 but it is not installable
PreDepends: libdirectfb-extra:i386 (>= 1.2.7-2) but it is not going to be installed
PreDepends: libxcb-render-util0:i386 (>= 0.3.6-1) but it is not installable
E: Unmet dependencies. Try 'apt-get -f install' …