Topic: Making custom Grids on Dimp.
When working with Dimp, and especially with the Preview (for lack of custom backgrounds), it's frequently really useful to create a custom Grid. This helps define a start-point for an animation, or an unchangeable concept, such as a floor.
Here's how it's done:
Select the Grid icon (selected in blue on the image).
A new border will appear around your canvas.
Within the border, you can now simply click to add Horizontal or Vertical lines.
Selecting the icon once more will remove the border but maintain the lines.
Note: In order to remove a line, simply select the Grid icon to activate the border and then select along the border to create a line in the exact same location as the line you would like to delete in order to "erase" it.

Hope that helps!
