Position According to Importance and Commonality
People tend to view panels from the top down and left to right. That means that the most important information should be positioned in the top left corner of the panel, and that information regarding a conclusion, such as "Okay" and "Cancel" buttons, should be placed in the bottom right corner.
Items on any panel should be positioned based on commonality. Things that all relate to each other should be clustered together with white space separating different clusters.
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Alignment
Attention should be paid to how design elements are aligned. There should be a focus on the horizontal and the vertical. Jagged columns of items that are not well aligned will cause the panel to appear cluttered, even if the number of items is not excessive.
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