I notice that often in Fontlab it wont let me place a node exactly where I want it to be. It is either a tiny bit over or a tiny bit under. Am I doing something wrong or is this typical behavior?

With Fontlab coordinates are always integer.

I'm not sure, and Claude can correct me if I'm wrong, but isn't the grid determined by the font's UPM size (usually 1000 or 2048)?

Je ne suis pas certain, et Claude pourra me corriger, mais la grille n'est elle pas déterminée par le 'UPM size' de la police (habituellement 1000 ou 2048)?

In Illustrator, you can have decimal but not in FontLab.

http://cjoint.com/13jn/CFzq7dmzgtp_what1.png

@JeremyWoods: Are you using the maximum enlargement View setting when you try to do this?

@JeremyWoods if you are referring to an outline imported from Illustrator, Fontlab will insist that nodes exactly fall on a unit. That is what usually causes the distortions when importing outlines from Illustrator or from a vector file. This is what Claude referred to when he mentioned integer (whole numbers) and decimal (with values in the decimal places). I've seen someone somewhere (can't remember) showed that floating points is possible but this is with respect to control points and not nodes.

@fmontpetit That is correct. Your maximum work area (ascender to descender) is 1000 units vertically on a 1000 UPM and 2400 units on a 2400 UPM if you want to get the correct line height. You can go over the number of units (for a given UPM) when drawing the font but you will end up with extra large glyphs or the line height will become too large to prevent avoid in Windows. And you won't hear Fontlab complain.

Please see the linked image to get a better idea of what I am talking about. I can get the selected node to be slightly to the left of the corrosponding line or slightly to the right but I can't get them to line up perfectly despite the other ends being connected. You should also know tht the second line is only there to serve as an example of how I can't get the first line exactly where I want it and the first line is meant to replace it.
http://imageshack.us/photo/my-images/545/8ae6.png/

I would like to see the 'Control Vectors' on your picture.

Play with the control vectors.

The answer is still the same, it is all about integer and decimal, and nodes must be located on a unit (integer).

Note that your line is diagonal. If you place a node somewhere between the two nodes of the straight line, the place where you want the node added will likely not fall on a unit. Although you are not actually placing a node on the straight line, aligninhg the node at the end of the curve to that line is practically doing that.

IMO the node at the end of the curve should be the node that should be moved and aligned to the line instead of the node at the end of the line. Move that node up or down by one unit and then move it one unit towards your "guide" line. You need to find on what position of the diagonal line falls exactly on a unit. You might even need to shift the 2 straight lines right or left. You can reshape the curve to what it was before when you have the node in place.

If you want to play some more, use guidelines. Create a diagonal guideline using the same angle as your line. Create a vertical and a horizontal guideline. Move the horizontal and vertical guidelines and find out where the three guidlines intersect. That location is where the node at the end of your curve should be. When you move the guidelines, make it one unit at a time so that you won't stray too far from the current position of the node. The vertical and horizontal guidelines' position is always an integer.

One other thing, is that straight line simply a line or a curve? If you did not intend it to be a curve make sure it is a line. Select the straight line (shift+click), right click on it and choose "Convert" -> "To Lines". It might have an effect on your difficluty in aligning if that's a curve instead of a line. Also, if those lines have control vectors/points, then it is not really a line but a curve.

BTW you will also see problems similar to this when you are merging objects if the place where the objects meet has a diagonal line or a curve.