Questions[gdebi](ubuntu)

I tried to install Docky from the official repositories via apt-get but it couldn't find the packet. So I downloaded the .deb from the web and tried a manual install with gdebi and this was the output:

$ sudo gdebi docky_2.2.1.1-1_all.deb 
Reading package lists... Done
Building dependency tree        
Reading state information... Done
Reading state information... Done
This package is uninstallable
Dependency is not satisfiable: libgconf2.0-cil (>= 2.24.0)

I couldn't find any info about why this packet is not usable. Is there any other way to install docky?

I'm trying to install Lightworks on my Ubuntu 19.10 desktop but when installing it, gdebi stops because it's missing the dependency 'libssl1.0.0'. Any advice will be helpful.

The link to the screenshot is the underlined sentence below.

I was trying to install DiffMerge. I downloaded the .deb package from the SourceGear website. But while installing it, it shows the following error

dependency is not satisfiable :libcurl3(>=7.16.2-1)

Can anyone please help me in solving this issue?
As I am studying Java, I need DiffMerge as it helps to compare the codes.

sudo apt-get install -f gdebi-core
[sudo] password for sdksdk:
Reading package lists ... Done
Building dependency tree
Loading state information ... Done
Gdebi-core package is not available, but is referred to by another package. This may mean,
that the package is missing, it has been obsoleted, or is only available from another source

I've noticed that Ubuntu 10.10 manages single .deb files with the Ubuntu Software Center. Since I find it too heavy to load I've installed gdebi with: sudo apt-get install gdebi and I've set it as default application to open any .deb file.

My question is: is it safe/supported to use this kind of operation? I mean: does gdebi still relate to internal apt-get to satisfy dependencies and install .deb files?