Window Hovering fading animation

It has been commented several times.
Here is a proof of concept that it can be done without any ImGui modification

This Lua code could be done with a class in C++ or a lambda function and provide us a function that when called from the window to be hovered returns a value in animated variation between two values

-- duration, min desired value, max desired value
local function HoverActionFactory(dur,minv,maxv)

	minv = minv or 0
	maxv = maxv or 1
	local range = maxv - minv
	local lastFrameHovered = false
	local actionTime = 0
	local actionUP = false
	local iniVal = 0
	local currVal = 0
	
	local function SetAction(dir)
		lastFrameHovered = dir
		actionTime = 0
		actionUP = dir
		iniVal = currVal
	end

	local function HoverAction()
		if ig.IsWindowHovered(imgui.ImGuiHoveredFlags_AllowWhenBlockedByPopup + imgui.ImGuiHoveredFlags_AllowWhenBlockedByActiveItem) then
			if not lastFrameHovered then SetAction(true) end
		elseif lastFrameHovered then
			SetAction(false)
		end
		local fac = actionTime/dur
		fac = actionUP and fac or -fac
		currVal = math.min(1,math.max(0,iniVal + fac))
		actionTime = actionTime + ig.GetIO().DeltaTime
		return minv + range*currVal
	end
	return HoverAction
end

To use it just use the HoverActionFactory as in

-- 0.5 sec transition from 0.001 to 1
local HoverAction = HoverActionFactory(0.5,0.0001,1)

And after ImGui::Begin

ig.PushStyleVarFloat(imgui.ImGuiStyleVar_Alpha, HoverAction())

Start with the issue's HoverActionFactory proof of concept and the named ImGui::Begin, ImGui::PushStyleVarFloat, ImGui::IsWindowHovered, and ImGui::GetIO entry points. Review how window hover state and style alpha are exposed, then define and validate a reusable transition API whose completion supports fading between the requested minimum and maximum values.