user: How do I use Transform in Blender? Include parameters, examples, warnings and best practices.

assistant: ### Move

Pressing `G` moves all the selected strip(s).
Move your mouse horizontally (left/right) to change the strip’s position in time.
Move vertically (up/down) to change channels.

Holding down `Ctrl` while dragging enables or disables snapping.

You can also lock the direction to time with `X` or to change the strip’s channel with `Y`.

It is possible to move strips using mouse by dragging them while holding `LMB`.
Currently it is possible to move only one strip by dragging.

#### Start Frame Offset

The *Start Frame Offset* for that strip can be selected by clicking `LMB` on the left handle of the strip;
holding it down (or pressing `G` and then moving the mouse left/right)
changes the start frame within the strip by the number of frames you move it.
The frame number label under the strip displays the start frame of the strip.

- If you have a 20-image sequence strip, and drag the left handle to the right by 10 frames,
  the strip will start at image 11 (images 1 to 10 will be skipped).
  Use this to clip off a roll-up or undesired lead-in.
- Dragging the left handle left will create a lead-in (copies) of the first frame for as many frames as you drag it.
  Use this when you want some frames for a transition at the start of the clip.

#### End Frame

The *End Frame* of the strip could be selected by clicking `LMB` on the right handle of the strip;
holding it down (or pressing `G`) and then moving the mouse changes the ending frame within the strip.
The frame number label over the strip displays the end frame of the strip.

- Dragging the right handle to the left shortens the clip;
  any original images at the tail are ignored. Use this to quickly clip off a roll-down.
- Dragging the right handle to the right extends the clip.
  For movies and images sequences, more of the animation is used until exhausted.
  Extending a clip beyond its length will render as a copy of the last image.
  Use this for transitions out of this clip.

### Move/Extend from Current Frame

With a number of strips selected, pressing `E` lets you interactively extend the strips.
This is similar to moving but is useful for extending (or shortening) time around the current frame.

All selected strip handles to the “mouse side” of the current frame indicator will transform together,
so you can change the duration of strips at the current frame.

### Slip Strip Contents

The *Slip Strip Contents* operator adjusts the start point of the source media inside a strip,
without changing the strip’s position or length on the timeline.
This is useful for fine-tuning what portion of the media is shown.

It is commonly used when you want to preserve the strip’s timing in the sequence
but choose a different part of the source to display.

Offset
:   Number of frames to shift the content forward (positive) or backward (negative) in time.

Slip Keyframes
:   If enabled, keyframes on the strip’s properties (e.g. opacity, transform) will be moved along
    with the content. Disable this to keep keyframes fixed at their original timeline positions.

Usage

Move the mouse left or right to shift the strip’s content, then confirm the operation.
Additional options are available during the operation:

- **Confirm**: `LMB`, `Return`, `Spacebar`
- **Cancel**: `Esc`, `RMB`
- **Precision Mode**: Hold `Shift` to enable subframe slipping which slips the audio.
  The subframe amount is shown in the header as *Sound Offset*.
- **Clamp**: Press `C` to clamp the slip range to the strip’s start and end bounds.

### Snap Strips to the Current Frame

Moves the strip or control point to the current frame.

### Clear Strip Offset

To reset the (soft) start/end frame handles.

### Swap Strip

Left `Alt`-`Left`
:   Swaps the active strip with the strip to the left.

Right `Alt`-`Right`
:   Swaps the active strip with the strip to the right.

### Remove Gaps

Remove blank frames between the current frame and the first strip to the left,
independent of selection or locked state of strips.

All Gaps
:   Remove gaps to the right of the strip along with the left.

### Remove Gaps (All)

Same as [Remove Gaps](#bpy-ops-sequencer-gap-remove) but with *All Gaps* enabled.

### Insert Gaps

Insert blank frames between the current frame and the first strips to the right,
independent of selection or locked state of strips.