Created attachment 157169 [details]
document to facitate testing

This will be a lengthy description, because there are many wrong statements.
The help page is found in 
file:///C:/Program%20Files/LibreOffice/help/en-GB/text/shared/main0227.html?DbPAR=SHARED#bm_id3149987
on my WWindoe´ws system or in
https://help.libreoffice.org/6.2/en-US/text/shared/main0227.html?DbPAR=SHARED
via Internet search, for example.

Main problem is the section "Convert To Curve". I have to pick individual sentences and comment them. The attached test document makes it easy to reproduce the described results, it contains a Bézier curve with some straight elements, and a polygon, if you wish to have another test case. Activate the point mode by clicking on "Points" in the Standard toolbar or using F8 for all the subsequent tests. And set the option to show all control points via Tools -> Options -> LibreOffice Draw -> View -> All control points in Bézier editor, because then you can see directly where the change to a curve has happened, without having to click at each curve point.

I first diecuss the problematic sentences, then offer a new text:
"If you select a single point, the curve before the point will be converted." This should read: "...curve _after_ the point...". To check: Select e.g. the point numbered 3, its colour will change to a light red ( I hope this is independent from the operation system), then click on the symbol "Convert to Curve".
Use "Undo" afterwards to revert to the previous situation, that makes the following tests easier.

Next sentence: "If two points are selected, the curve between both points will be converted." Wrong: Select points 3 and 4 and use again "Convert to Curve": the two sections after these points will be converted. And use Undo afterwards.

Next sentence: "If you select more than two points, each time that you click this icon, a different portion of the curve will be converted." In all my tests, with one exemption I cannot reproduce, _all_ portions or segments were converted. Test it by selecting points 3, 5 and 6, e.g.

Next sentence: "If necessary, round points are converted into corner points and corner points are converted into round points."
"round points" is a term not used in the tool bar; if it means smooth an d syyymetruic, then the first part is correct, the second part isn't: when converting straight line into curves the angle at the points is kept.

Next sentences: "If a certain section of the curve is straight, the end points of the line have a maximum of one control point each. They cannot be modified to round points unless the straight line is converted back to a curve."
The second sentence is definitively wrong, you can convert these points to corner points, smooth transition and symmetric transition. Without the second sentence the first has no relevance, too.


So here is my proposal:
Converts a curve (as part of a polygon or Bézier shape) into a straight line or converts a straight line into a curve. If you select a single point, the curve after the point will be converted. If you select more than one point, the curves after each of these curves will be converted. When converting to straight lines, the points will normally be converted to corner points.

There is another bug #105988 dealing with similar problems which should be tackled in conjunction with this one.

And a minor issue is that in the first sentence of the named page "...select a polygon object ..." there should be added "or Bézier shape".