ipos | IP over SMS- leveraging SMS to provide IP connectivity | SMS library

You really need to enable the debugging validation layer and check errors, because there's a whole bunch of easily catchable misconceptions in your code:

1. Don't use glBindAttribLocation. iPos is already (correctly) bound to layout location 0, you're just breaking it.

2. You didn't detach and delete your shader programs after you linked the program, thus leaking the memory.

3. Don't unbind the vertex and element buffers from your vertex array, that's the whole point of using it in the first place.

4. Related to 3, don't change the vertex and element buffers of your vertex array every render. You set up a vertex buffer once.

5. You're telling OpenGL that your index elements are bytes in your glDrawElements and instead you upload them as 32-bit integers. Be consistent.

The issue seems to be that the simulation is not being "reheated" when adding a new node with the context menu. Reheating the simulation is a "soft restart" process that makes the nodes move again, which is needed when adding new data or during interactions. Without reheating, the interaction only works while the simulation is still active (i.e, when the alpha haven't decayed to 0 yet). This is why the first nodes are ok, and the third or fourth are buggy: by that time, the simulation already settled and it will not move by itself anymore.

You are already reheating the simulation when there is a drag start event (dragStarted):

This is rather theoretical question. If sockets I/O (either read or write) is set to O_NONBLOCK, but then this socket is set in fd_set to select() which blocks (waiting for an event the file descriptor become either readable or writable), then that socket is blocking anyway (due to the select())?

The select is blocking. The socket is still non-blocking.

Why would I set the socket to be non-blocking, when even the blocking (default) version once become readable (or writable) (thanks to select()), won't block, because the select() said it has data to read (or write) and thus the socket is able to perform its operation with that data without blocking.

No, no, no! That is not a safe assumption. There is no guarantee that a subsequent read or write will not block. You must set the socket non-blocking if you need a future guarantee that a later operation will not block.

So why to bother setting socket non-blocking when select() blocks anyway?

Because you don't want operations on the socket to block. The select function does not guarantee that a future operation won't block and people have gotten burnt by making that assumption in the past.

For example, you do select on a UDP socket and it says that a receive won't block. But before you call recv, the administrator enables UDP checksums which were previously disabled. Guess what, now your recv will block if the checksum was incorrect on the only received datagram.

Unless you think you could have foreseen every way something like that could happen, and you definitely can't, you must set the socket non-blocking if you do not wish it to block.

The key issue is that you need to re-initialize the force layout after you add a node:

Use TStringList.CustomSort to sort the list using a specific method for comparison.

The specification for the comparer is given here.

Example:

To summarize an answer from comments:

Your problem comes from the fact that you add a lot of empty rows because you set RowCount equal to RowMax. Once sorted, the empty cells goes to the top of the list.

There are two solutions:

1. You stop adding empty lines and sorting will be as expected
2. Manage to sort with a comparer that makes empty string BIGGER as all other string instead of the default which is smaller. See the documentation for CustomSort

Note that you can change the row count at anytime. Just assign the RowCount property. For example, when you add a row, do:

First, I'd transform your ListingDate into a POSIXct object (this is just a way to store dates and times in their own format instead of text) and select the first semester. Using the package ludibriate, you can do this (I got inspiration from this place

in case param is NaN you can break the for loop to exit the loop or you can continue to the next param.

I think you should use focus() method.