cx16: retain display mode (composite etc)

compiler/res/prog8lib/cx16/gfx2.p8

@@ -82,11 +82,10 @@ gfx2 {
                 bpp = 2
             }
             else -> {
-                ; back to default text mode and colors
-                cx16.VERA_CTRL = %10000000      ; reset VERA and palette
-                c64.IOINIT()
-                c64.RESTOR()
+                ; back to default text mode
+                cx16.r15L = cx16.VERA_DC_VIDEO & %00000111 ; retain chroma + output mode
                 c64.CINT()
+                cx16.VERA_DC_VIDEO = (cx16.VERA_DC_VIDEO & %11111000) | cx16.r15L
                 width = 0
                 height = 0
                 bpp = 0

compiler/res/prog8lib/cx16/syslib.p8

@@ -613,12 +613,19 @@ asmsub  init_system()  {
     %asm {{
         sei
         cld
+        lda  VERA_DC_VIDEO
+        and  #%00000111 ; retain chroma + output mode
+        sta  P8ZP_SCRATCH_REG
         lda  #$80
-        sta  VERA_CTRL
+        sta  VERA_CTRL  ; reset vera
         stz  $01        ; select rom bank 0 (enable kernal)
         jsr  c64.IOINIT
         jsr  c64.RESTOR
         jsr  c64.CINT
+        lda  VERA_DC_VIDEO
+        and  #%11111000
+        ora  P8ZP_SCRATCH_REG
+        sta  VERA_DC_VIDEO  ; keep old output mode
         lda  #$90       ; black
         jsr  c64.CHROUT
         lda  #1         ; swap fg/bg

examples/cx16/testgfx2.p8

@@ -1,22 +1,22 @@
 %import gfx2
 %import textio
-%import test_stack
 %import math
 
+%option no_sysinit
+%zeropage basicsafe
+
 
 main {
 
     sub start() {
         gfx2.screen_mode(5)
 
-;        demo1()
-;        sys.wait(3*60)
+        demo1()
+        sys.wait(2*60)
         demo2()
 
         gfx2.screen_mode(0)
         txt.print("done!\n")
-
-        test_stack.test()
     }
 
     sub demo1() {