VSE: Tool system integration

Add toolbar to sequencer regions.

A bit of refactoring has to be done in RNA space.
Currently there is only cut tool implemented to serve as template for
anybody who would like to add more.

release/scripts/startup/bl_ui/space_sequencer.py

@@ -30,6 +30,9 @@ from bpy.app.translations import (
 from bl_ui.properties_grease_pencil_common import (
     AnnotationDataPanel,
 )
+from bl_ui.space_toolsystem_common import (
+    ToolActivePanelHelper,
+)
 from rna_prop_ui import PropertyPanel
 
 
@@ -89,6 +92,35 @@ def draw_color_balance(layout, color_balance):
     split.template_color_picker(color_balance, "gain", value_slider=True, lock_luminosity=True, cubic=True)
 
 
+class SEQUENCER_PT_active_tool(ToolActivePanelHelper, Panel):
+    bl_space_type = 'SEQUENCE_EDITOR'
+    bl_region_type = 'UI'
+    bl_category = "Tool"
+
+
+class SEQUENCER_HT_tool_header(Header):
+    bl_space_type = 'SEQUENCE_EDITOR'
+    bl_region_type = 'TOOL_HEADER'
+
+    def draw(self, context):
+        layout = self.layout
+
+        layout.template_header()
+
+        self.draw_tool_settings(context)
+
+        # TODO: options popover.
+
+    def draw_tool_settings(self, context):
+        layout = self.layout
+
+        # Active Tool
+        # -----------
+        from bl_ui.space_toolsystem_common import ToolSelectPanelHelper
+        tool = ToolSelectPanelHelper.draw_active_tool_header(context, layout)
+        tool_mode = context.mode if tool is None else tool.mode
+
+
 class SEQUENCER_HT_header(Header):
     bl_space_type = 'SEQUENCE_EDITOR'
 
@@ -97,7 +129,10 @@ class SEQUENCER_HT_header(Header):
 
         st = context.space_data
 
-        layout.template_header()
+        show_region_tool_header = st.show_region_tool_header
+
+        if not show_region_tool_header:
+            layout.template_header()
 
         layout.prop(st, "view_type", text="")
 
@@ -226,6 +261,7 @@ class SEQUENCER_MT_view(Menu):
             # wm_keymap_item_find_props() (see #32595).
             layout.operator_context = 'INVOKE_REGION_PREVIEW'
         layout.prop(st, "show_region_ui")
+        layout.prop(st, "show_region_toolbar")
         layout.operator_context = 'INVOKE_DEFAULT'
 
         if is_sequencer_view:
@@ -2131,6 +2167,7 @@ class SEQUENCER_PT_custom_props(SequencerButtonsPanel, PropertyPanel, Panel):
 
 classes = (
     SEQUENCER_MT_change,
+    SEQUENCER_HT_tool_header,
     SEQUENCER_HT_header,
     SEQUENCER_MT_editor_menus,
     SEQUENCER_MT_range,
@@ -2156,7 +2193,7 @@ classes = (
     SEQUENCER_MT_strip_input,
     SEQUENCER_MT_strip_lock_mute,
     SEQUENCER_MT_context_menu,
-
+    SEQUENCER_PT_active_tool,
     SEQUENCER_PT_strip,
 
     SEQUENCER_PT_effect,