Long arrows bug in LaTeX

I recently noticed there is a bug when using the equation editor to render

\Longrightarrow

or

\Longleftarrow

Long arrows are made of an equal sign and an arrow, glued together. The problem is the two symbols do not both scale by the same amount, when changing the font size. This is not a bug in the equation editor, but within LaTeX itself, as described in this bug fix request: <a href="http://www.latex-project.org/cgi-bin/ltxbugs2html?pr=mfnfss/3741">http://www.latex-project.org/cgi-bin/ltxbugs2html?pr=mfnfss/3741</a>

The solution is to use proper combinations of point sizes and DPI values, so that the long arrow displays correctly. I noticed that there are only two fonts that can be used to properly render long arrows - Sans Serif and Comp Modern. I created a table with the proper combinations for each of these fonts:

<table border="1"> <tr> <th>Font</th> <th>Point size</th> <th>Valid DPI values</th> </tr> <tr> <td>Sans Serif</td> <td>(8pt) Tiny</td> <td>100, 120, 150, 300</td> </tr> <tr> <td></td> <td>(10pt) Small</td> <td>80, 110, 120, 150</td> </tr> <tr> <td></td> <td>(12pt) Normal</td> <td>100, 150, 300</td> </tr> <tr> <td></td> <td>(14pt) Large</td> <td>50, 80, 110, 120</td> </tr> <tr> <td></td> <td>(20pt) Huge</td> <td>50, 80</td> </tr> <td>Comp Modern</td> <td>(8pt) Tiny</td> <td>100, 110, 120, 300</td> </tr> <tr> <td></td> <td>(10pt) Small</td> <td>80, 110, 120, 150</td> </tr> <tr> <td></td> <td>(12pt) Normal</td> <td>100, 150</td> </tr> <tr> <td></td> <td>(14pt) Large</td> <td>50, 80, 110, 120</td> </tr> <tr> <td></td> <td>(20pt) Huge</td> <td>50, 80</td> </tr> </table>