I have a Centos 7 system with vinagre-3.22.0. It works well except for two major annoyances I'd like to figure out how to fix:

1. The Ctrl modifier is not transmitted from Centos to Windows. All other modifiers (Shift, Alt) are sent, as well as the "Windows" key that brings up the Start menu on Windows. Only Ctrl seems to be blocked. For example, when in the Windows RDP session Ctrl+V "paste" just enters "v" instead of pasting. Ctrl+C in a cmd window just enters the character "c".
   
   Curiously, this seems to affect multiple RDP clients, as it exhibits the same behavior with Remmina, so this may be an RDP issue not specific to vinagre.
   
   
2. While I can move windows on the Windows desktop just fine, I cannot RESIZE them. When hovering over the window border the cursor does not change into a resize cursor, and I cannot drag the border. The workaround is to use the top-left titlebar icon, select "Size", type any arrow key, and then use the mouse to set the new size. Is there a reason hovering over the window border does not work?
   
   Interestingly, a few applications provide an explicit "resize" corner at the bottom right (looks like a triangle of gray dots) and I CAN click on this and drag to resize that specific application. If the application does not provide this then the normal resize behavior cannot be accessed.
   
   This problem affects Remmina as well.

Suggestions on settings to tweak to make these two issues go away would be greatly appreciated.

For anyone who runs into the same issue, here's the solution.

After much digging through all possible configuration dialogs I discovered that in the Gnome desktop configuration there is an option to highlight the mouse cursor position by pressing the Ctrl key. This seems to be enabled by default and causes Gnome to trap Ctrl-key keypresses to produce a flashing effect around the mouse cursor.

Turning this off stops Gnome from intercepting Ctrl, and it is passed to the remote system as expected.

For some reason, this ALSO almost totally fixes the resize issue. I say "almost" because the mouse cursor does not change to indicate resize functionality, but I can now drag the window border as expected.

The setting in question is under Applications/Accessories/Tweaks/Keyboard&Mouse, and is called "Pointer Location". If this setting is enabled, Gnome captures Ctrl to flash the mouse cursor. With this setting DISABLED, Ctrl is passed to the remote system as expected.