I am using Ubuntu 16.04 LTS with Unity on WSL and VCXSrv on Windows 10 Home on a Dell Inspiron 1545. I have a problem when opening a program such as Firefox from the panel:
That's possibly due to limited RAM(My laptop has like 3GB RAM).

WSL - you mean Windows Subsystem for Linux? Doesn't that run a Linux instance on top of Windows? With only 3 GB of RAM you're lucky to be able to run Windows by itself, must less throwing another graphical OS on top of it. Have you looked at your system resource usage while doing this?

Also this question really doesn't apply to the thread (a thread which is marked as solved, and likely won't see many, if any views), I recommend reporting it and requesting that a mod move your question to its own thread where people might see it.

1 members found this post helpful.

Moved your post from non-related thread to a thread of it's own.

Seems to have lost some context - and the subject is now meaningless.
Why ?. How ?.
I had a look at WSL when it first became available, but only so I could use grep and awk on the (rare) occasions I actually booted Win10. Everything I have just seen suggests the GUI hacks are subject to frequent failure - as you seem to have found out.
Why is that a surprise ?.