user: What is Header and how is it used in Blender Python scripting?

assistant: [image reference removed]

Video Sequencer Header.

### View Menu

The View menu controls the editor’s view settings.

Toolbar `T`
:   Show or hide the [Toolbar](../../../interface/tool_system.xhtml#ui-region-toolbar).

Sidebar `N`
:   Show or hide the [Sidebar](../../../interface/window_system/regions.xhtml#ui-region-sidebar).

Tool Settings
:   Show or hide the settings for the currently selected tool.

Adjust Last Operation
:   Displays a pop-up panel to alter properties of the last
    completed operation. See [Adjust Last Operation](../../../interface/undo_redo.xhtml#bpy-ops-screen-redo-last).

Channels
:   Show or hide the [Channel Region](channels.xhtml#bpy-types-sequencetimelinechannel).

Playback Controls
:   Show or hide the [Playback Controls](../../../animation/animation_editors.xhtml#animation-editors-footer).

---

Refresh All `Ctrl`-`E`
:   Reloads external files and refreshes the current frame preview.
    This is useful when you modified an external file or made a change in a scene that Blender
    didn’t detect.

---

Frame Selected `NumpadPeriod`
:   Zooms the display to show only the selected strips.

Frame All `Home`
:   Zooms the display to show all strips.

Frame Scene/Preview Range
:   Reset the horizontal view to the current scene frame range,
    taking the preview range into account if it is active.

Go to Current Frame `Numpad0`
:   Centers the horizontal timeline on the current frame.

Zoom to Border `Shift`-`B`
:   Click and drag to draw a rectangle and zoom to this rectangle.

Limit View to Contents
:   Prevents you from panning higher than the highest used channel.

---

Show Markers
:   Shows the marker region. When disabled, the *Marker* menu is also hidden
    and marker operators are not available in this editor.

Use Timecode `Ctrl`-`T`
:   Shows seconds instead of frames on the time axis.

Sync Visible Range
:   Synchronizes the horizontal panning and scale of the editor
    with other time-based editors that also have this option enabled.
    That way, they always show the same section of time.

---

Navigation
:   Play Animation `Spacebar`
    :   Start or stop animation playback. This will start playback in all editors.

    Go to Current Frame `Numpad0`
    :   Scrolls the timeline so the current frame is in the center.

    Jump to Previous Strip `PageUp`
    :   Moves the playhead to the nearest strip border (start or end) that’s before the current frame.

    Jump to Next Strip `PageDown`
    :   Moves the playhead to the nearest strip border (start or end) that’s after the current frame.

    Jump to Previous Strip (Center) `Alt`-`PageUp`
    :   Moves the playhead to the nearest strip center that’s before the current frame.

    Jump to Next Strip (Center) `Alt`-`PageDown`
    :   Moves the playhead to the nearest strip center that’s after the current frame.

Range
:   Set Preview Range `P`
    :   Interactively define the frame range used for preview playback/rendering.

        As long as this range is active, playback will be limited to it, letting you repeatedly view a
        segment of the video without having to manually rewind each time. It also limits the range
        that gets rendered by *Sequence Render Animation* (see below).

    Set Preview Range to Strips
    :   Apply a preview range that encompasses the selected strips.

    Clear Preview Range `Alt`-`P`
    :   Clears the preview range.

    Set Start Frame `Ctrl`-`Home`
    :   Set the Start frame of the scene to the current frame.

    Set End Frame `Ctrl`-`End`
    :   Set the End frame of the scene to the current frame.

    Set Frame Range to Strips
    :   Set the Start and End frames of the scene so they encompass the selected strips.

---

Sequence Render Image
:   Show the current frame preview as a Render Result where you can save it as an image file.

Sequence Render Animation
:   Save previews of the frames in the scene range (or the preview range, if active) to a video file
    or a series of image files. See the [Output](../../../render/output/properties/output.xhtml) panel for details.

---

Export Subtitles
:   Exports [Text strips](../../../video_editing/edit/montage/strips/text.xhtml),
    which can act as subtitles, to a [SubRip](https://en.wikipedia.org/wiki/SubRip) file (`.srt`).
    The exported file contains all Text strips in the video sequence.

---

Toggle Sequencer/Preview `Ctrl`-`Tab`
:   Switch the editor mode between *Sequencer* and *Preview*.

---

Area
:   Area controls. See the [user interface](../../../interface/window_system/areas.xhtml)
    documentation for more information.

### Marker Menu

[Markers](../../../animation/markers.xhtml) are used to denote frames with key points or significant events
within an animation. Like with most animation editors, markers are shown at the bottom of the editor.

[image reference removed]

Markers in animation editor.

See [Editing Markers](../../../animation/markers.xhtml#animation-markers-editing) for details.

### Sequencer Scene

A [data-block menu](../../../interface/controls/templates/data_block.xhtml#ui-data-block) to select a scene.
The [Sequencer Scene](../../../video_editing/sequencer_scene.xhtml)
is the scene that the edit shown in the Sequencer is contained in.