Vim has two registers for interacting with X text selection and clipboard. In your question you mention that you tried the
"* register, but there is another register for yanking to and putting from the X clipboard, namely
"+. As long as vim is built with X11 support (which the
vim-gtk package has), both vim and gvim use these two registers for working with the X selection and clipboard buffers. Use the
"* register if you want to paste text that has been highlighted with the mouse and use
"+ to paste text that has been copied to the clipboard from another program.
Paste from the clipboard in normal mode
To paste from the X clipboard into a vim buffer while in normal mode, use
"+gP depending on whether you want the text to be inserted before or after the cursor location and where you want the cursor to end up after pasting. See
:help put in vim.
Paste from the clipboard in insert mode
If you are in insert mode in a vim buffer and want to paste the contents of the clipboard, use Ctrl+r and
+. This will insert the clipboard text at the cursor location and keep you in insert mode to continue entering text after what was pasted. See
:help i_CTRL-R in vim.
Paste from the clipboard in command mode
Pasting from the clipboard in command mode (while entering commands after
:) is exactly the same as in insert mode, use Ctrl+r followed by
+. So, referring to your original example of copying a file name in the system's file browser, you could open that file in vim by starting the command
:e, then Ctrl+r, and then
+ to paste the file name. See
:help c_CTRL-R in vim.
Vim has a large set of registers, some of which are general purpose for the user, and some of which have specific functions. For more information about Vim registers in general, see
:help registers in Vim's manual. For more about the difference between the X selection and clipboard buffers, see
:help x11-selection. And the specific uses of the
"+ registers are described in
:help quotestar and