The Hydrogen user interface is designed so that it can be used entirely with the mouse, with the exception of text entry.
Most actions are performed with the left mouse button, and implement what should be the most obvious behaviour for any control. The right mouse button may sometimes perform an alternate action, or bring up a context menu. Some common controls also have alternate actions accessed by clicking while holding a modifier key:
Ctrl + left click : restore default value of knob or fader
Shift + left click : bind MIDI event to MIDI-learnable widget (see Section 16.2)
Some controls will also respond to scroll wheel events for convenience.
The keyboard can also be used for navigating and editing in the Pattern and Song Editors, using a combination of
↑|↓|←|→ : move the keyboard input cursor's position, or adjust values under the cursor.
Shift + ↑|↓|←|→ : can be used to make selections of notes or pattern groups as if the mouse had been dragged over them.
Enter and Return : generally performs the same action as a mouse click, but can also start or end a move (or copy) of items in the same way a mouse drag would.
Tab and Shift + Tab : move between the Pattern, Song and Note Property Editor.
Delete : delete notes or patterns.
Esc : cancels an ongoing selection, move or copy.
![[Note]](../img/admonitions/note.svg) | Note |
|---|---|
The keyboard input cursor is hidden from view until one of the above keys is pressed. This keeps the display clear and uncluttered when using the mouse. You can alter this default behavior in the General tab of the Preferences. |
Most other keys on the keyboard can be used to play samples and enter notes in the same way a MIDI keyboard can be.