Activate GL context after polling events each frame, bump version

Makefile

@@ -1,5 +1,5 @@
 RACK_DIR ?= .
-VERSION = 0.6.2b
+VERSION = 0.6.2c
 
 FLAGS += \
 	-Iinclude \

src/window.cpp

@@ -439,6 +439,7 @@ void windowRun() {
 
 		// Poll events
 		glfwPollEvents();
+		glfwMakeContextCurrent(gWindow);
 		{
 			double xpos, ypos;
 			glfwGetCursorPos(gWindow, &xpos, &ypos);