The native access functions for context handles did not verify that the
context had been created with the same API the function was for.
This makes these functions emit GLFW_NO_WINDOW_CONTEXT on API mismatch.
This adds the glfwInitAllocator function for specifying a custom memory
allocator to use instead of the C runtime library.
The allocator is a struct of type GLFWallocator with fields
corresponding to malloc, realloc and free, while the internal API
corresponds to calloc, realloc and free.
Heap allocation calls are filtered before reaching the user-provided
functions, so deallocation of NULL and allocations of zero bytes are not
passed on, reallocating NULL is transformed into an allocation and
reallocating to size zero is transformed into deallocation.
The clearing of a new block to zero is performed by the internal
calloc-like function.
Closes#544.
Fixes#1628.
Closes#1947.
DWM composition is always enabled on Windows 8 and later, so there's no
need to call DwmIsCompositionEnabled on those platforms.
Fixes#1452.
Closes#1453.
This completes support for window framebuffer transparency on Windows,
macOS and X11. Note that the hint/attribute may be renamed before
release to clarify its relationship to GLFW_OPACITY.
Fixes#197.
Closes#1079.
Related to #663.
Related to #715.
Related to #723.
Related to #1078.
PFN_FunctionName is more readable than SCREAMSOUP_T.
Context creation API function typedefs are kept as-is where the original
header provided them, for compatibility and familiarity reasons.
This removes window re-creation logic by performing the initial context
creation on the helper window, simplifying both window and context
creation and paving the way for attaching to existing window handles
without compromising on context or framebuffer hint support.
