Allow undo a single step

[humdingerb]

Add an icon button with a tool tip for that. Only allow one undo step!

[scottmc]

Fixed by #11

[tuankiet65]

Fixed by #17

[scottmc]

Can you download the current code and try to build it? Do it in a clean directory so you don't lose other work. I just merged two pull requests, but not it fails to compile. Maybe you can spot what happened?

[tuankiet65]

I will in the next two or three hours I think, I'm doing school work right now.

[tuankiet65]

@scottmc

~/tmp/Haiku2048> make
mkdir -p objects.x86-cc2-release; \
mkdepend  -I./  -Iobjects.x86-cc2-release/ -p .cpp:objects.x86-cc2-release/%n.o -m -f "objects.x86-cc2-release/WindowBoard.d" WindowBoard.cpp
g++ -c WindowBoard.cpp  -I./  -Iobjects.x86-cc2-release/ -I-   -O3    -o "objects.x86-cc2-release/WindowBoard.o"
/boot/home/tmp/Haiku2048/WindowBoard.cpp: In method `void GameWindow::FrameResized(float, float)':
/boot/home/tmp/Haiku2048/WindowBoard.cpp:189: implicit declaration of function `int SetScale(...)'
/boot/system/develop/etc/makefile-engine:291: recipe for target 'objects.x86-cc2-release/WindowBoard.o' failed
make: *** [objects.x86-cc2-release/WindowBoard.o] Error 1

Probably from pull request #18