UI: Add new theme, update theme capabilities

I have always felt that the out of the box themes for OBS were quite
lacking, and have spent a lot of time going through and sorting out the
difficulties with the current setup. I've added a new themeID parameter to
several elements that were otherwise impossible to target with QSS in a
theme. Since Qt has pushed for the use of QML over QSS at this point,
these should be considered workarounds. Included is the theme I was
working on that can serve as a base. I'm hoping to encourage others to
make their own themes, so we can grow the available themes for OBS.

I am happy for any feedback on the theme itself, or other updates that
can me made to make creating new themes easier overall.

UI/hotkey-edit.cpp

@@ -272,10 +272,12 @@ void OBSHotkeyWidget::AddEdit(obs_key_combination combo, int idx)
 	edit->setToolTip(toolTip);
 
 	auto revert = new QPushButton;
+	revert->setProperty("themeID", "hotkeyButtons");
 	revert->setText(QTStr("Revert"));
 	revert->setEnabled(false);
 
 	auto clear = new QPushButton;
+	clear->setProperty("themeID", "hotkeyButtons");
 	clear->setText(QTStr("Clear"));
 	clear->setEnabled(!obs_key_combination_is_empty(combo));
 
@@ -287,10 +289,12 @@ void OBSHotkeyWidget::AddEdit(obs_key_combination combo, int idx)
 	});
 
 	auto add = new QPushButton;
+	add->setProperty("themeID", "hotkeyButtons");
 	add->setText("+");
 	add->setMinimumWidth(50);
 
 	auto remove = new QPushButton;
+	remove->setProperty("themeID", "hotkeyButtons");
 	remove->setText("-");
 	remove->setEnabled(removeButtons.size() > 0);
 	remove->setMinimumWidth(50);

UI/properties-view.cpp

@@ -296,6 +296,7 @@ void OBSPropertiesView::AddPath(obs_property_t *prop, QFormLayout *layout,
 		button->setEnabled(false);
 	}
 
+	button->setProperty("themeID", "settingsButtons");
 	edit->setText(QT_UTF8(val));
 	edit->setReadOnly(true);
 	edit->setToolTip(QT_UTF8(obs_property_long_description(prop)));
@@ -610,6 +611,7 @@ QWidget *OBSPropertiesView::AddButton(obs_property_t *prop)
 	const char *desc = obs_property_description(prop);
 
 	QPushButton *button = new QPushButton(QT_UTF8(desc));
+	button->setProperty("themeID", "settingsButtons");
 	button->setSizePolicy(QSizePolicy::Maximum, QSizePolicy::Maximum);
 	return NewWidget(prop, button, SIGNAL(clicked()));
 }
@@ -628,6 +630,7 @@ void OBSPropertiesView::AddColor(obs_property_t *prop, QFormLayout *layout,
 		colorLabel->setEnabled(false);
 	}
 
+	button->setProperty("themeID", "settingsButtons");
 	button->setText(QTStr("Basic.PropertiesWindow.SelectColor"));
 	button->setToolTip(QT_UTF8(obs_property_long_description(prop)));
 
@@ -698,6 +701,7 @@ void OBSPropertiesView::AddFont(obs_property_t *prop, QFormLayout *layout,
 	font = fontLabel->font();
 	MakeQFont(font_obj, font, true);
 
+	button->setProperty("themeID", "settingsButtons");
 	button->setText(QTStr("Basic.PropertiesWindow.SelectFont"));
 	button->setToolTip(QT_UTF8(obs_property_long_description(prop)));
 
@@ -1795,6 +1799,7 @@ public:
 		if (browse) {
 			QPushButton *browseButton =
 				new QPushButton(QTStr("Browse"));
+			browseButton->setProperty("themeID", "settingsButtons");
 			topLayout->addWidget(browseButton);
 			topLayout->setAlignment(browseButton, Qt::AlignVCenter);
 

UI/window-basic-main.cpp

@@ -1213,6 +1213,7 @@ void OBSBasic::ResetOutputs()
 					this,
 					&OBSBasic::ReplayBufferClicked);
 
+			replayBufferButton->setProperty("themeID", "replayBufferButton");
 			ui->buttonsVLayout->insertWidget(2, replayBufferButton);
 		}