Added layout debugging.

dvx/dvxApp.c

@@ -54,7 +54,10 @@ static void compositeAndFlush(AppContextT *ctx) {
         // 1. Draw desktop background
         rectFill(d, ops, dr->x, dr->y, dr->w, dr->h, ctx->colors.desktop);
 
-        // 2. Walk window stack bottom-to-top
+        // 2. Draw minimized window icons (under all windows)
+        wmDrawMinimizedIcons(d, ops, &ctx->colors, ws, dr);
+
+        // 3. Walk window stack bottom-to-top
         for (int32_t j = 0; j < ws->count; j++) {
             WindowT *win = ws->windows[j];
 
@@ -77,10 +80,7 @@ static void compositeAndFlush(AppContextT *ctx) {
             }
         }
 
-        // 2b. Draw minimized window icons
-        wmDrawMinimizedIcons(d, ops, &ctx->colors, ws, dr);
-
-        // 3. Draw popup menu if active
+        // 4. Draw popup menu if active
         if (ctx->popup.active) {
             // Draw popup dropdown
             RectT popRect = {
@@ -484,25 +484,40 @@ void dvxQuit(AppContextT *ctx) {
 // ============================================================
 
 void dvxRun(AppContextT *ctx) {
-    while (ctx->running) {
-        pollMouse(ctx);
-        pollKeyboard(ctx);
-        dispatchEvents(ctx);
-
-        if (ctx->dirty.count > 0) {
-            compositeAndFlush(ctx);
-        } else {
-            // Nothing to do — yield timeslice
-            __dpmi_yield();
-        }
-
-        ctx->prevMouseX       = ctx->mouseX;
-        ctx->prevMouseY       = ctx->mouseY;
-        ctx->prevMouseButtons = ctx->mouseButtons;
+    while (dvxUpdate(ctx)) {
+        // dvxUpdate returns false when the GUI wants to exit
     }
 }
 
 
+// ============================================================
+// dvxUpdate
+// ============================================================
+
+bool dvxUpdate(AppContextT *ctx) {
+    if (!ctx->running) {
+        return false;
+    }
+
+    pollMouse(ctx);
+    pollKeyboard(ctx);
+    dispatchEvents(ctx);
+
+    if (ctx->dirty.count > 0) {
+        compositeAndFlush(ctx);
+    } else {
+        // Nothing to do — yield timeslice
+        __dpmi_yield();
+    }
+
+    ctx->prevMouseX       = ctx->mouseX;
+    ctx->prevMouseY       = ctx->mouseY;
+    ctx->prevMouseButtons = ctx->mouseButtons;
+
+    return ctx->running;
+}
+
+
 // ============================================================
 // dvxShutdown
 // ============================================================

dvx/dvxApp.h

@@ -48,6 +48,10 @@ void dvxShutdown(AppContextT *ctx);
 // Run the main event loop (returns when ctx->running is set to false)
 void dvxRun(AppContextT *ctx);
 
+// Process one iteration of the event loop.
+// Returns true if the GUI is still running, false if it wants to exit.
+bool dvxUpdate(AppContextT *ctx);
+
 // Create a window
 WindowT *dvxCreateWindow(AppContextT *ctx, const char *title,
                           int32_t x, int32_t y, int32_t w, int32_t h,

dvx/dvxWidget.h

@@ -446,6 +446,13 @@ void wgtListBoxSetItems(WidgetT *w, const char **items, int32_t count);
 int32_t wgtListBoxGetSelected(const WidgetT *w);
 void wgtListBoxSetSelected(WidgetT *w, int32_t idx);
 
+// ============================================================
+// Debug
+// ============================================================
+
+// Draw borders around layout containers in ugly colors
+void wgtSetDebugLayout(bool enabled);
+
 // ============================================================
 // Layout (called internally; available for manual trigger)
 // ============================================================

dvx/widgets/widgetCore.c

@@ -6,10 +6,11 @@
 // Global state for drag and popup tracking
 // ============================================================
 
-WidgetT *sOpenPopup    = NULL;
-WidgetT *sDragSlider   = NULL;
+bool     sDebugLayout   = false;
+WidgetT *sOpenPopup     = NULL;
+WidgetT *sDragSlider    = NULL;
 WidgetT *sDrawingCanvas = NULL;
-int32_t  sDragOffset   = 0;
+int32_t  sDragOffset    = 0;
 
 
 // ============================================================

dvx/widgets/widgetInternal.h

@@ -42,6 +42,7 @@
 // Shared state (defined in widgetCore.c)
 // ============================================================
 
+extern bool     sDebugLayout;
 extern WidgetT *sOpenPopup;
 extern WidgetT *sDragSlider;
 extern WidgetT *sDrawingCanvas;

dvx/widgets/widgetOps.c

@@ -3,6 +3,40 @@
 #include "widgetInternal.h"
 
 
+// ============================================================
+// debugContainerBorder
+// ============================================================
+//
+// Draw a 1px border in a garish neon color derived from the widget
+// pointer so every container gets a distinct, ugly color.
+
+static void debugContainerBorder(WidgetT *w, DisplayT *d, const BlitOpsT *ops) {
+    static const uint8_t palette[][3] = {
+        {255,   0, 255},  // magenta
+        {  0, 255,   0},  // lime
+        {255, 255,   0},  // yellow
+        {  0, 255, 255},  // cyan
+        {255, 128,   0},  // orange
+        {128,   0, 255},  // purple
+        {255,   0, 128},  // hot pink
+        {  0, 128, 255},  // sky blue
+        {128, 255,   0},  // chartreuse
+        {255,  64,  64},  // salmon
+        { 64, 255, 128},  // mint
+        {255, 128, 255},  // orchid
+    };
+
+    uint32_t h   = (uint32_t)(uintptr_t)w * 2654435761u;
+    int32_t  idx = (int32_t)((h >> 16) % 12);
+    uint32_t color = packColor(d, palette[idx][0], palette[idx][1], palette[idx][2]);
+
+    drawHLine(d, ops, w->x, w->y, w->w, color);
+    drawHLine(d, ops, w->x, w->y + w->h - 1, w->w, color);
+    drawVLine(d, ops, w->x, w->y, w->h, color);
+    drawVLine(d, ops, w->x + w->w - 1, w->y, w->h, color);
+}
+
+
 // ============================================================
 // widgetPaintOne
 // ============================================================
@@ -80,6 +114,9 @@ void widgetPaintOne(WidgetT *w, DisplayT *d, const BlitOpsT *ops,
 
         case WidgetTabControlE:
             widgetTabControlPaint(w, d, ops, font, colors);
+            if (sDebugLayout) {
+                debugContainerBorder(w, d, ops);
+            }
             return; // handles its own children
 
         case WidgetStatusBarE:
@@ -92,6 +129,9 @@ void widgetPaintOne(WidgetT *w, DisplayT *d, const BlitOpsT *ops,
 
         case WidgetTreeViewE:
             widgetTreeViewPaint(w, d, ops, font, colors);
+            if (sDebugLayout) {
+                debugContainerBorder(w, d, ops);
+            }
             return; // handles its own children
 
         default:
@@ -102,6 +142,11 @@ void widgetPaintOne(WidgetT *w, DisplayT *d, const BlitOpsT *ops,
     for (WidgetT *c = w->firstChild; c; c = c->nextSibling) {
         widgetPaintOne(c, d, ops, font, colors);
     }
+
+    // Debug: draw container borders on top of children
+    if (sDebugLayout && w->firstChild) {
+        debugContainerBorder(w, d, ops);
+    }
 }
 
 
@@ -310,6 +355,15 @@ void wgtPaint(WidgetT *root, DisplayT *d, const BlitOpsT *ops,
 }
 
 
+// ============================================================
+// wgtSetDebugLayout
+// ============================================================
+
+void wgtSetDebugLayout(bool enabled) {
+    sDebugLayout = enabled;
+}
+
+
 // ============================================================
 // wgtSetEnabled
 // ============================================================