OpenGL stores the current context in thread-local memory, but commit
4f5baa9a51 removed a runtime.LockOSThread from app.Window that ensured
the goroutine that drives the context stays on the operating thread that
has the context current. This change restores the thread lock.
As a bonus, this change makes the OpenGL contexts responsible for locking
the thread at MakeCurrent, thereby removing LockOSThread calls from GPU
backend-agnostic code.
Fixes: https://todo.sr.ht/~eliasnaur/gio/334
Signed-off-by: Elias Naur <mail@eliasnaur.com>
The app and app/internal/wm packages are tightly coupled, requiring
quite a bit of forwarding types, values and constants from the internal
package to export it. Further, no other package imports package wm.
This change merges the two packages.
While here, drop the pre-Go 1.14 SIGPIPE workaround.
Signed-off-by: Elias Naur <mail@eliasnaur.com>