What's the meaning of the "key" symbols in Altium?

I'm routing a PCB board with Altium. Today I find when my mouse hover on the pads, it shows some shadowed "key" symbols. What's the meaning of them?

The "key" symbol means that the specific track/pad/component is in locked position, so it is unmovable. Right click on the [specific item $\longrightarrow$ properties $\longrightarrow$ uncheck locked checkbox] and the "key" symbols will be gone.