How to drop files from Desktop to Finder windows in a sane way? I know this question looks like a joke, but I've been using Macbooks for a few years and I've never found the right way of dropping files from Desktop to other windows.

Imagine this scenario: I'm on Yosemite, talking on Slack, having some files on Desktop I want to share with on my Slack channel, how do I drag these files from desktop to Slack window? Normally I have to:


go trough all the windows that are below the Slack window &amp; minimize them (pain in the a...), this step is not actually a step but usually like 30 steps as I have that many apps working in the background,
resize Slack window to half the screen so I can see the Desktop, 
drop the files from desktop on Slack.


While on Windows 7/8 it looks like:


click on right bottom corner,
click on Slack window,
resize Slack window,
drag &amp; drop.


I tried to use the same flow on OSX, so I have "Show Desktop" set as a hot corner, I move to that corner, I can see the desktop but this feature is useless compared to the same functionality in Windows as if I click any app all the windows come back to their places...

How do you do that guys? Can I somehow set hot corner to minimize all windows instead of just showing Desktop for a second? How's that useful?
There are multiple ways to achieve it. 

Using hot corners


Slide Your mouse to the hot corner to show Desktop
Drag Your file (do not drop)
Slide once again to hot corner
Drop the file to the app 


Using keyboard shortcuts


Show Desktop with ⌃ CTRL+↓ Down arrow
Drag the file (You may need to click on Desktop first to activate Finder)
Then ⌘ CMD+⇥ TAB to previous app and drop it


Using the trackpad


Show Desktop with gesture (spread four fingers on trackpad)
Drag the file
Slide on top of the app icon on Dock
Slide on top of the window You want
Drop the file