Difficulty Zooming into Multi-Line Equations

## Version

MathCAT 0.7.5

## Issue

Within multi-line equation blocks, I am unable to zoom into the elements of any particular line unless I use Ctrl + Shift + Down, which zooms in maximally. I am unable to easily zoom in by one level.

### Example

$$\begin{aligned}
\frac{dx}{dt} &= ax + by\\
\frac{dy}{dt} &= cx + dy
\end{aligned}$$
