elseif(eventArg == "PLAYER_REGEN_DISABLED") then
RogueFocus.InCombat = true;
elseif(eventArg == "PLAYER_REGEN_ENABLED") then
RogueFocus.InCombat = false;
There is code specifically in there to turn the frame on/off when you enter/exit combat. PLAYER_REGEN_DISABLED occurs when you enter combat just before "framelockdown" occurs. PLAYER_REGEN_ENABLED occurs when you exit combat just after "frame unlockdown" occurs.
I assume this is to prevent the frame from being moved in combat by disabling mouse events, since trying to do so will generate an action blocked error.
When you do Framename:EnableMouse(false), that frame will no longer receive any mouse events, its as though the frame is not there at all.
This means that mouse OnEnter, OnLeave, OnClick, OnMouseScroll, etc etc will all be dormant and you cannot interact with the frame with the mouse in any manner.
Nothing will set a frame's EnableMouse to true, except for button:Enable() for the frame type "button". button:Disable() will set EnableMouse to false, along with changing the color and look to the disabled settings of that button.