I had the same problem: blank lines in latex articles produces a clearly separated paragraph, but in Beamer, with the limited space and no indentation, the default new paragraph is does not strikingly separate the paragraphs.
My hack solution was to append the following latex code to the end of the paragraph that should have the space.
\\~\
For example, try inserting this into a Beamer latex file:
\frame{
This is text that should have a blank line after it. \\~\\
Here is text following a blank line.
}
if the last line of your paragraph is really nearly full, you can get it to end flush right by the following approach.
wrap the paragraph in braces.
end the paragraph with these commands (inside the braces):
\unskip\parfillskip 0pt \par
update: a mechanism that doesn't require braces.
before the paragraph, insert
\startsquarepar
at the end of the paragraph, insert
\stopsquarepar
define these two commands in the preamble as follows:
\newcommand{\startsquarepar}{%
\par\begingroup \parfillskip 0pt \relax}
\newcommand{\stopsquarepar}{%
\par\endgroup}
it's not necessary to have blank lines either before or after either of these commands
(the grouping and included \par ensures that that's not a problem), but readability
and "good practice" suggests that a blank line before \startsquarepar and one after
\stopsquarepar is a good idea.
blank lines within the scope of \startsquarepar and \stopsquarepar will start new
paragraphs as expected, and all paragraphs within this scope will end flush right --
whether or not there's the right amount of material in each paragraph to avoid excessive spacing.
why didn't i use \begin... and \end...? while there are no "strings" attached to
\begin..., latex has co-opted the use of \end... for its own purposes in defining
environments. if you really prefer the \begin ... \end terminology and environment
syntax, it's easy to transform the two command definitions given into a single
environment definition. (but left as an exercise to the reader.)
edit: one final suggestion from egreg's comment (to keep it from getting lost).
{{\parfillskip0pt\par}} can be a useful for a manual solution as it
doesn't need bracing the paragraph.
Best Answer
This is LyX's way of staying true to LaTeX where successive blank lines are merged - a good thing when you're talking about consistent document layout/design. If you wish to insert a forced vertical skip, insert an ERT containing either
\smallskip,\medskip,\bigskipor a fixed\vspace{<len>}where you specify<len>. For a fixed/hard, single blank line, use\vspace{\baselineskip}(roughly the same as\bigskip).The other lengths that were mentioned are "softer" and allow for some stretch/shrink.
For consistency, you can also increase the skip between paragraphs (known as
\parskip) under Document > Settings... > Text Layout > Separate paragraphs with > Vertical space: