Onscreen rulers definitely belong in that class of PC tools that are useful enough to keep around but all too often overlooked. A Ruler For Windows (AR4F) is a free onscreen metric ruler that offers attractive skins and handy keyboard commands. It toggles into a reading guide, a straight bar for distinguishing fine lines of print and closely spaced text.
AR4F's default skin is an attractive wood-grain look. It's ruled for millimeters and marked every 100mm. A red line displays its position on the ruler, allowing for easy readouts of fine measurements. AR4F is easy to resize via small controls at either end, and the program displays the ruler's total length in green at the right end. The controls on the left select magnification level, and the measurement marks at the top or bottom edge of the ruler toggle between horizontal and vertical modes, depending on whether we right-clicked or left-clicked the button. The Themes button let us change the interface color to yellow, stainless steel (gray) or plastic (semitransparent). We could also directly enter a specific length for our ruler, which is handy if you know how long something should be: Just set the ruler to that length for quick matching. The right-side controls minimize or close AR4F and open the combined Options-Help-About sheet. This lists the program's mouse commands and keyboard shortcuts and offers checkboxes for a few options, including Help balloons, confirm exit, and enabling the fence ruler/reading guide. We selected this option and clicked OK. The keyboard shortcut for toggling to the reading guide is S; we pressed it, and the ruler minimized to a straight bar about two lines of text high, with the controls visible when we hovered the cursor at either end.
A Ruler For Windows is one of the nicer tools of its type we've tried--clearly marked, with useful controls. It needs U.S.-style measurements (inches, etc.) and picas wouldn't hurt, either; those additions would make it much more versatile. But we have no qualms about recommending A Ruler For Windows.