Intel partition: activate the first created partition.

The default MBR relies on at least one partition being active. The first
one sounds like a good choice.

Fixes #7930.

src/add-ons/disk_systems/intel/PartitionMapAddOn.cpp

@@ -301,7 +301,9 @@ PartitionMapHandle::GetParameterEditor(B_PARAMETER_EDITOR_TYPE type,
 	if (type == B_CREATE_PARAMETER_EDITOR
 		|| type == B_PROPERTIES_PARAMETER_EDITOR) {
 		try {
-			*editor = new PrimaryPartitionEditor();
+			BMutablePartition* partition = Partition();
+			int32 count = partition->CountChildren();
+			*editor = new PrimaryPartitionEditor(count == 0);
 		} catch (std::bad_alloc) {
 			return B_NO_MEMORY;
 		}

src/add-ons/disk_systems/intel/PrimaryParameterEditor.cpp

@@ -19,12 +19,15 @@
 #define B_TRANSLATION_CONTEXT "PrimaryPartitionEditor"
 
 
-PrimaryPartitionEditor::PrimaryPartitionEditor()
+PrimaryPartitionEditor::PrimaryPartitionEditor(bool first)
 {
 	fActiveCheckBox = new BCheckBox("active", B_TRANSLATE("Active partition"),
 		NULL);
 	fView = new BGroupView(B_VERTICAL);
 	fView->AddChild(fActiveCheckBox);
+
+	// The first partition is active by default. Others are not.
+	fActiveCheckBox->SetValue(first);
 }
 
 

src/add-ons/disk_systems/intel/PrimaryParameterEditor.h

@@ -16,7 +16,7 @@
 
 class PrimaryPartitionEditor : public BPartitionParameterEditor {
 public:
-								PrimaryPartitionEditor();
+								PrimaryPartitionEditor(bool first);
 	virtual						~PrimaryPartitionEditor();
 
 	virtual		BView*			View();