时间轴是作为谷歌仲夏之码活动（Google Summer of Code 2017）的一部分开发的，并首次在MuseScore 3.0中引入。
This is found in the top right corner of the timeline. These hold the meta values of the score.
This is found in the bottom right corner of the timeline. This holds multiple 'cells' (a specific measure and staff in the score represented as a square)
Meta are elements found on the score that are not notes, but are still important to the score (key signature, time signature, tempo, rehearsal marks, bar lines, and jumps and markers).
Holding Shift and holding the left mouse button and dragging the mouse over the main grid will create a selection box. Upon releasing the mouse button, all the cells underneath the selection box will be selected, as well as all the measures in the score.
If a cell is already selected, holding Shift and selecting another cell in the timeline will stretch the selection to that new cell, similar to how the score does
If no cells are currently selected, holding Ctrl and selecting a cell will select the entire measure
Meta values selection
Selecting the meta values on the timeline will attempt to select the respective meta values in the score.
All meta labels besides the measures meta may be rearranged in any way. By moving the mouse cursor onto one of the meta labels, small up and down arrows will appear. Click the left mouse button on the up arrow to swap the meta label with the one above it. Click the left mouse button on the down arrow to swap the meta label with the one below it.
Collapsing the meta labels
In order to hide all the meta labels while keeping all the meta information on the timeline, there is an arrow that appears on the measures meta when the mouse is over it. Click the left mouse button on the large up arrow to collapse all the currently visible meta rows into one row, where the meta values are staggered in that row. Click the left mouse button on the large down arrow to expand the meta rows again.
All instruments--hidden or not--will be displayed on the timeline. To start this interaction, the mouse cursor is moved over an instrument label. A small eye will appear on the right side of the label that is open if the instrument is visible on the score, and closed if the instrument is hidden. Click the left mouse button on the eye to toggle between the two options.
To bring up a context menu, right click on the timeline. There are three context menus found in these locations: meta labels, instrument labels, and meta rows.
Meta labels context menu
Upon clicking the right mouse button on the meta labels, a context menu appears that displays all possible meta labels as well as two options: "Hide all" and "Show all." Next to each meta label in the menu, there is a check box that shows if the meta label is currently being shown on the timeline. To show or hide one of the meta labels, select the box of the meta label in the context menu. Selecting "Hide all" will hide all meta labels except for the measures meta. Selecting "Show all" will display all meta labels.
Meta rows context menu
Clicking the right mouse button on the meta rows will display the same context menu as the meta labels.
Instrument context menu
Clicking the right mouse button on the instrument labels will display a context menu with the option to "Edit Instruments." Selecting this will bring you to the same dialog as Edit > Instruments... or pressing I for the shortcut.