Viewing CSS property value suggestions in Notepad++

Question

Using Notepad++ 5.7

I was modifying a .css file, when I blocked/selected a rule and accidentally pressed a key in combination with alt or ctrl and other keys in the lower left-hand side of the keyboard...not sure which keys.

Moving on, a list of CSS values came up such as :first-letter a few hundred more. What key commands are needed to achieve this again and where is the documentation for this feature? I find it fascinating.

Code I selected at the time:

input[type=reset]:hover, input[type=submit]:hover{
color:#ffffff;
background-color:#1c1c1c;
cursor:pointer;
border:2px groove #0e0e0e;
-webkit-border-radius: 5px;
-moz-border-radius: 5px;
border-radius: 5px;

}