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,
Code:
<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:
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.