GPv3: Tint tool UI fixes

This PR contains 3 fixes in the tool bar for the Tint tool:
- For the tint color, the general color panel was shown, but it should
be the Grease Pencil color panel (with not just the color wheel, but
also the color palettes).
- The Advanced Brush panel was redundant, because it only showed
Radius and Strength and those are already present in the tool bar.
So the Advanced panel can be removed.
- The 'Active Layer' switch wasn't exposed in the tool bar, so it has
been added.

Pull Request: https://projects.blender.org/blender/blender/pulls/120719

scripts/startup/bl_ui/properties_paint_common.py

@@ -1515,8 +1515,8 @@ def brush_basic_grease_pencil_paint_settings(layout, context, brush, *, compact=
         layout.prop(gp_settings, "use_active_layer_only")
     elif grease_pencil_tool == 'TINT':
         layout.prop(gp_settings, "vertex_mode", text="Mode")
-        layout.popover("VIEW3D_PT_tools_brush_settings_advanced", text="Brush")
         layout.popover("VIEW3D_PT_tools_brush_falloff")
+        layout.prop(gp_settings, "use_active_layer_only")
 
 
 def brush_basic_gpencil_sculpt_settings(layout, _context, brush, *, compact=False):

scripts/startup/bl_ui/space_view3d.py

@@ -671,7 +671,8 @@ class _draw_tool_settings_context_mode:
             brush_basic__draw_color_selector(context, layout, brush, brush.gpencil_settings, None)
 
         if grease_pencil_tool == 'TINT':
-            UnifiedPaintPanel.prop_unified_color(row, context, brush, "color", text="")
+            row.separator(factor=0.4)
+            row.prop_with_popover(brush, "color", text="", panel="TOPBAR_PT_gpencil_vertexcolor")
 
         from bl_ui.properties_paint_common import (
             brush_basic__draw_color_selector,