Unable to open the pakset installer if Simutrans is fullscreen/borderless

[Roboron]

Requisites:
1. Microsoft Windows
2. Simutrans 123 SDL2 or GDI

Steps to reproduce:
1. Open simutrans with -borderless or -fullscreen launch parameter and at least one pakset installed.
2. Click "Install" on the pakset selection screen.
3. Pakset installer opens, but simutrans becomes unresponsive and you are unable to switch to the pakset installer until simutrans is killed.

Explanation: It seems that Microsoft Windows will make any fullscreen application exclusive (it doesn't matter if it is true fullscreen or just borderless), and thus prevent any application from being shown when Simutrans becomes unresponsive.

Some possible solutions:
1. Prevent simutrans from becoming unresponsive (obviously). I have not looked at why it becomes unresponsive.
2. Integrate the installer into simutrans as it is in Linux/Mac?
3. Workaround the Windows bug feature, at least for borderless fullscreen, as explained here https://discourse.libsdl.org/t/true-borderless-fullscreen-behaviour/24622/16 (don't like, dirty solution)

[prissi]

Well, the installer has jsut to remove fullscreen attribute from it temporary. Seems to work without side effects in r10344

[Roboron]

Yes it does. Thank you very much.