Moving a selection horizontal or vertical is easy when using the hor.- or vert. keyboard arrows.
But then you are restricted to a certain discrete step. To fine tune the move, I have to use my mouse and
then there is the problem to get an exact horizontal or vertical moving of the selection.
Is there a trick to overcome this? Tried several things (pressing the Ctrl key for instance) but nothing does the trick.

Using Ctrl should work. What happens when you use Ctrl (meaning Ctrl-click, keep Ctrl pressed and move object)? Isn't the movement restricted hor/ver?

That's it!!
I first have to press the Ctrl, and then select what I want and when I move it, it is in either
horizontal or vertical way when using the mouse. Did not come up with this sequence myself .
Thank you Bart!

Edit: Sorry, sent twice!

For very fine movements, hold Alt while moving with the arrow keys, zoom in to make the movement still finer - it will move by 1 screen pixel.
See also: https://inkscape.org/en/doc/keys091.html

Or if you need a very specific movement, you could change the X value on the Selection control bar, without changing the Y value (for horizontal movement) (For vertical, change the Y but not the X value.) Or the spinboxes of the X and Y values will move by 0.1 of whatever the unit is.

brynn wrote:Or if you need a very specific movement, you could change the X value on the Selection control bar, without changing the Y value (for horizontal movement) (For vertical, change the Y but not the X value.) Or the spinboxes of the X and Y values will move by 0.1 of whatever the unit is.

brynn, sorry for my late reply but for some reason I did not receive a response notification.
Can you be more specific please? I see on the bottom righ corner the X,Y display of the coordinates of the mouse but not that of the selected line. Must overlook something I guess.

The control bar is the 3rd major bar from the top of the Inkscape window. It contains the options for the various tools. So for the Selection tool, it's the Selection tool control bar. If you were using the Node tool, it's called the Node tool control bar. I don't know why it's not just called The Control Bar, but I've been corrected when I say it that way.

Anyway, on that bar, you have various icons/buttons and some fields for number values. X tells you where the object is, from left to right. Y tells you where the selected object is from top to bottom. You may remember plotting coordinates in math class, in school, where there is an x value and a y value, and you count the marks on the x and y axis? (You're analog man, you should know that, right?) That's how Inkscape works!

Then there's also a W which shows the width of the selection and H shows the height, on the Selection control bar.

The X and Y values in the bottom right corner, that change all the time, are telling you where you mouse/cursor is. You can't change those, they are just for information.

So if you need to move an object or a node by some certain amount....let's say 10 pixels, then you can change the X value by either +10 or -10 depending on which direction you need it to move. Or you can use the spinbox (tiny, tiny, up and down arrows beside the number field). 1 click on the up or down arrow will change the value in the field (and move the node or object) by + or - 0.100 pixel (or whatever the unit is). I use that fairly often, because you can move in one tenth of a pixel, while using Alt + arrow key doesn't move the node or object by any specific amount. (And you have to be zoomed in really far for Alt + arrow to move such a small distance.) However, this only works for horizontal and vertical movements. You'd have to do a lot of math to calculate any other kind of movement.

Starting with version 0.91, you can let Inkscape do the math. Let's say you have an object at the coordinates (10,20) which means it's 10 pixels from the left side of the page and 20 pixels up from the bottom. Let's say you need to move the object to the point (20,20). So in the X field, where it says 10.000, you can type a plus sign " + " and "10" (on the right side of "10.000" then press enter, and Inkscape does the calculation, and moves the object, at the same time.

Well, those are simple numbers, but what if your node or object was at 2597.539? For myself, I'm not afraid of simple math, and I would just do it myself. But some developer thought it would be useful, and now Inkscape can do that

brynn, thank you very much for your elaborate reply! I have copied and paste this in a (Writer) document for reference.
It is now clear for me how to proceed when dealing with these kind of things in Inkscape .