Fix #2944: Fix cursor alpha issues

[Lpsd]

Resolves #2944

• Don't allow setCursorAlpha executed via Lua script(s) to affect the cursor alpha if the main menu or console is visible

Additional issues resolved (not mentioned in #2944):

• Server cursor alpha not correctly restored if console is hidden using the escape key (instead of the console key bind)
• Closing the console with the main menu visible would restore the server's cursor alpha

A basic clientside script can be found below to perform all the tests necessary

function setCursorAlphaCommand(cmd, amount)
    amount = tonumber(amount) and math.max(0, math.min(255, amount)) or 0
    setCursorAlpha(amount)
    iprint("cursor alpha", amount, "@" .. getTickCount())
end
addCommandHandler("cursor", setCursorAlphaCommand)

bindKey("F2", "down", function()
    showCursor(not isCursorShowing())
end)

Usage:

• /cursor <alpha> to set the cursor alpha
• F2 toggles (on/off) the cursor visiblity

Test cases:

• When calling setCursorAlpha with the main menu or console visible, it will not be applied
• When closing the main menu or console, the server's last set cursor alpha value (via setCursorAlpha) will be applied
  • Note: Not applicable if the console is closed whilst the main menu is visible. In this case, the main menu must also be closed for the server's cursor alpha to be applied.
  • Improvement: When closing the console (without the main menu visible) using the escape key, the server's cursor alpha will now be applied.

[patrikjuvonen]

Thank you, tested lightly and seems to be working as expected.