[ProPain]

I managed to reassign the F12 hotkey in Civ so it won't interfere with the F12 Steam screenshot key anymore. Took a bit more effort than expected because G&K introces a second shortkey file which sort of screwed me over the first time.

First find the file that applies to your civ version

Non G&K civ V

- goto
...steam\steamapps\common\sid meier's civilization V\assets\gameplay\XML\units


G&K civ V

goto
....Steam\steamapps\common\Sid Meier's civilization V\assets\DLC\Expansion\gameplay\xml\units\Civ5cont rols.XML

make a copy for safety reasons
open it in a texteditor
look for: KB_F12,

		
		<Row>
			<Type>CONTROL_QUICK_LOAD</Type>
			<Description>TXT_KEY_ACTION_QUICK_LOAD</Description>
			<Help/>
			<DisabledHelp/>
			<HotKey>KB_F12</HotKey>
			<AltDown>0</AltDown>
			<ShiftDown>0</ShiftDown>
			<CtrlDown>0</CtrlDown>
			<HotKeyPriority>0</HotKeyPriority>
			<HotKeyAlt/>
			<AltDownAlt>0</AltDownAlt>
			<ShiftDownAlt>0</ShiftDownAlt>
			<CtrlDownAlt>0</CtrlDownAlt>
			<HotKeyPriorityAlt>0</HotKeyPriorityAlt>
		</Row>

Replace KB_F12 with any KB_[yourkey] but make sure that you dont use a key that's already used by Civ V.
If you wanna use a Shift/Alt/Control with your new hotkey set the appropiate xxxxDown trigger to 1.
Save and done.

I set it to Alt-L as that appeared to be free, you get the following code:

		<!-- edited F12 to Alt L for screenie reasons -->
		<Row>
			<Type>CONTROL_QUICK_LOAD</Type>
			<Description>TXT_KEY_ACTION_QUICK_LOAD</Description>
			<Help/>
			<DisabledHelp/>
			<HotKey>KB_L</HotKey>
			<AltDown>1</AltDown>
			<ShiftDown>0</ShiftDown>
			<CtrlDown>0</CtrlDown>
			<HotKeyPriority>0</HotKeyPriority>
			<HotKeyAlt/>
			<AltDownAlt>0</AltDownAlt>
			<ShiftDownAlt>0</ShiftDownAlt>
			<CtrlDownAlt>0</CtrlDownAlt>
			<HotKeyPriorityAlt>0</HotKeyPriorityAlt>
		</Row>

While trying to find a solution I edited both files, I'm not sure if editing only the G&K file will suffice. Also I didn't check if both files are identical or differ at some point.