You can use vertical and horizontal rulers at the left and upper edges of the LibreOffice Impress workspace to assist you in creating your slide. The sections of the rulers that cover the area of the slide are white.
When you select an object, its dimensions are displayed on the rulers as grey double lines. To precisely resize the object, drag one of the double lines to a new location on the ruler.
When you select a text object on a slide, indents and tabs are displayed on the horizontal ruler. To change the indent or tab settings for the text object, drag an indent or a tab stop marker to a new location on the ruler.
You can also drag a snap line from a ruler to help you align objects on your slide. To insert a snap line using a ruler, drag the edge of a ruler into the slide.
To show or hide the rulers, choose View - Rulers.
To specify the measurement units for a ruler, right-click the ruler, and then choose a new unit from the list.
To change the origin (0 point) of the rulers, drag the intersection of the two rulers in the top left corner into the workspace. Vertical and horizontal guides appear. Continue to drag until the vertical and horizontal guides are where you want the new origin to be, and then release. To reset the origins of the rulers to the default values, double-click the intersection.
To change the slide margins, drag the edge of the white areas in the rulers.