This is a prerequisite for making ScrollPanel work nicely on touch screens.
Engine used the terms MouseClick and MouseUnclick to refer to events that are traditionally called MouseDown and MouseUp, this was fixed with simple renaming.
Component and friends similarly used the terms MouseClick and MouseUnclick to refer to events that are traditionally called MouseDown and MouseUp and, succumbing to their own confusing terminology, also implemented behaviours associated with both the actual events MouseDown and MouseClick in code that was responsible for handling only the actual event MouseDown (i.e. what they called MouseClick).
This had been overlooked for a long time because nobody cares that a checkbox changes state when the mouse button is pressed on it rather than when it is released.
The fix is to migrate many pieces of code that run in response to MouseDown events, such as checkbox state change code, to MouseClick events, and to redefine a MouseClick to mean a sequence of MouseDown and MouseUp inside the component, rather than just a MouseDown. This is complicated by the fact that MouseClick events report mouse coordinates relative to the top left corner of the component, while MouseDown events report them relative to the top left corner of the container of the component.
Other pieces of code that make sense to be run in response to MouseDown events, such as label selection code, were left alone.
Still currently in process, there are some issues:
Windows version doesn't work, mac version might not work, opengl might not work
Icon doesn't work (on Linux at least)
Lua will need some changes, there are some sdl 1.2 hacks in there
When entering fullscreen, the window loses focus
When holding down mouse out of bounds, mouse move events stop being sent
When letting go of mouse out of bounds, mouseup event doesn't take into account double scale mode
Clicking on startup without moving mouse will draw at 0,0 for a frame
Renderer probably won't compile because USE_SDL doesn't entirely work
... and maybe others
Some nice things were done though:
no more blit2, sdl can do the scaling itself
3d effect removed, no reason to support this joke any longer
No need to support copy/paste ourselves, sdl does it now
text handling done much better now, separate events for key presses and text input
when a new window is shown, all events ignored until next tick (ignore textinput event if window shown from key press event like console)
you can get current OS / build information, exe name, restart tpt, open a link in the web browser, and use clipboard copy/paste functions
Also remove some older Platform.h file which wasn't really needed or used
