We have these shortcuts for zooming the timeline:
"Application-Sequence-Zoom In/Out"
"Application-Zoom to Frame"
"Application-Zoom to Sequence"

The first one is tied to a specific panel, the two last ones are tied to the active panel.
The last two only change the zoom level of the timeline. But the first one "Sequence-Zoom" zooms the active panel. So when I'm in the Source or Program Monitor (I like switching between them with the "Toggle Src-Prg Monitor") I cannot zoom into the timeline.
There should be different shortcuts for zooming the timeline/timebar of the monitors and the behaviour of "Sequence-Zoom" should match the behaviour of "Zoom to frame" and "Zoom to sequence", being basically a application wide shortcut for the timeline panel.
At the moment it's a little inconsistent with the given shortcuts