In node (slave) detail information page (url: /computer/node_name) these is a text box showing the reason why the node is offline. But this offline reason doesn't shown on node monitor page (url: /computer) nor Build Executor Status box. User has to click into the node to check the reason. It's inconvenient when a lot of nodes are offline.

The idea is to show offline reason on node list and Build Executor Status box. The text could be in a floating box which shows when mouse hover.