Toggling a breakpoint presents inconsistencies between UI and logic

[oxcabe]

Description

The "toggle breakpoint" UI is not in sync with the underlying state of the breakpoints.

Reproducing

1. Navigate to the superscalar machine.
2. Load the example code.
3. Set a breakpoint at instruction 0 by clicking on the instruction line. The red circle that indicates a breakpoint will not show up.
4. Start an execution by pressing the Play button. The breakpoint will trigger and the red circle will appear.

The opposite scenario is occurring as well, where the dot might still show after disabling the breakpoint.

Solution

• Investigate what causes this bug and fix it.
• Improve breakpoint accessibility, possibly by displaying a tooltip when hovering on top of the instruction number.
• Narrow breakpoint setting surface to only cover the instruction number slot.