remove workaround for [#34346], checked on applying this workaround for armatures too but it happens in more cases then I originally thought.

for now users of opensource Nouveau and ATI drivers can't use multiple windows, the bug needs to be fixed in the driver.

source/blender/editors/interface/interface_draw.c

@@ -61,15 +61,6 @@
 /* own include */
 #include "interface_intern.h"
 
-/* only for bug workaround [#34346] */
-#if !defined(WIN32) && !defined(__APPLE__)
-#  define GPU_OSS_BUG_WOKAROUND
-#endif
-
-#ifdef GPU_OSS_BUG_WOKAROUND
-#  include "GPU_extensions.h"
-#endif
-
 static int roundboxtype = UI_CNR_ALL;
 
 void uiSetRoundBox(int type)
@@ -1245,7 +1236,6 @@ void ui_draw_but_COLORBAND(uiBut *but, uiWidgetColors *UNUSED(wcol), rcti *rect)
 
 void ui_draw_but_NORMAL(uiBut *but, uiWidgetColors *wcol, rcti *rect)
 {
-	static int use_displist = -1;
 	static GLuint displist = 0;
 	int a, old[8];
 	GLfloat diff[4], diffn[4] = {1.0f, 1.0f, 1.0f, 1.0f};
@@ -1294,20 +1284,12 @@ void ui_draw_but_NORMAL(uiBut *but, uiWidgetColors *wcol, rcti *rect)
 		size = BLI_rcti_size_y(rect) / 200.f;
 	
 	glScalef(size, size, size);
-	
-#ifdef GPU_OSS_BUG_WOKAROUND
-	if (use_displist == -1) {
-		use_displist = !GPU_type_matches(GPU_DEVICE_ANY, GPU_OS_UNIX, GPU_DRIVER_OPENSOURCE);
-	}
-#endif
 
-	if (displist == 0 || use_displist == 0) {
+	if (displist == 0) {
 		GLUquadricObj *qobj;
 
-		if (use_displist) {
-			displist = glGenLists(1);
-			glNewList(displist, GL_COMPILE_AND_EXECUTE);
-		}
+		displist = glGenLists(1);
+		glNewList(displist, GL_COMPILE);
 		
 		qobj = gluNewQuadric();
 		gluQuadricDrawStyle(qobj, GLU_FILL);
@@ -1316,14 +1298,11 @@ void ui_draw_but_NORMAL(uiBut *but, uiWidgetColors *wcol, rcti *rect)
 		glShadeModel(GL_FLAT);
 		gluDeleteQuadric(qobj);
 		
-		if (use_displist) {
-			glEndList();
-		}
-	}
-	else {
-		glCallList(displist);
+		glEndList();
 	}
 
+	glCallList(displist);
+
 	/* restore */
 	glDisable(GL_LIGHTING);
 	glDisable(GL_CULL_FACE);